See Page 3
FUNDAMENTAL
CHARACTERISTICS AND
APPLICATION POTENTIAL
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CORELESS PRINTED
CIRCUIT BOARD (PCB)
TRANSFORMERS—
A
ISSN 1049-3654
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Volume 11, Number 3, Third Quarter 2000
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and
Systems
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JUNE
MARCH
THE INSTITUTE OF
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Coreless Printed Circuit
Board (PCB) Transformers
– Fundamental Characteristics
and Application Potential
S. Y. (Ron) Hui
A
bstract – In this article, the
fundamental concept, characteristics and application potentials of
coreless printed-circuit-board (PCB)
transformers are described. Coreless
PCB transformers do not have the
limitations associated with magnetic
cores, such as the frequency limitation, magnetic saturation and core
losses. In addition, they eliminate the
manual winding process and its associated problems, including labor
cost, reliability problems and difficulties in ensuring transformer quality
in the manufacturing process. The parameters of the printed windings can
be precisely controlled in modern
PCB technology. Because of the drastic reduction in the vertical dimension, coreless PCB transformers can
achieve high power density and are
suitable for applications in which
stringent height requirements for the
circuits have to be met. A transformer’s
power density of 24W/cm2 has been
S. C. Tang
H. Chung
reported in a power conversion application. When used in an isolation amplifier application, coreless PCB
transformers tested so far enable the
amplifier to achieve a remarkable linear frequency range of 1MHz, which
is almost eight times higher than the
frequency range of 120 kHz in existing Integrated-Circuit products. PCB
materials offer extremely high isolation voltage, typically from 15kV to
40kV, which is much higher than many
other isolation means such as optocouplers. It is envisaged that coreless
PCB transformers can replace traditional core-based transformers in
some industrial applications. Their application potentials deserve more attention and exploration.
Introduction
The discovery of Faraday’s law of
induction is indisputably a corner stone
in electrical and electronic engineering. The consequent development of
. . . continued on Page 4
3
Figure 1. Photograph of a coreless PCB
transformer (right) and a core-based
transformer (left).
Coreless PCB Transformers … continued from Page 3
electric generators and transformers
has made electricity a common form
of energy in modern society. These
days, transformers are commonly used
for electrical isolation and energy and/
or signal transfer. Normally, traditional
transformers consist of copper windings wound on magnetic cores. The
use of magnetic cores in transformers
is usually thought to be essential because the magnetic cores, which are
made of ferromagnetic materials, provide good conducting paths for the
magnetic flux. The core-based transformer concept has not faced much
serious challenge in the past, probably
because of the fact that most transformer designs were for low-frequency
(50 or 60Hz) operations. Even when
the operating frequency in many modern power electronics applications
(such as switched mode power supplies) was significantly increased to
several hundreds of kilo-Hertz in the
1990’s, the core-based transformer
concept remained more or less intact.
Although it is well known that the size
of the magnetic components decreases
with increasing operating frequency,
the issue: “When will the size of the
magnetic components approach zero and
become zero?” was seldom addressed.
The main reasons for the use of
magnetic cores are primarily to pro4
vide a high degree of magnetic coupling and to reduce the leakage inductance. Transformers formed by using
twisted coils without magnetic cores
have been proposed [1] for high-frequency applications. In [1], it was
demonstrated that the twisted-coil
transformers could achieve a coupling factor of 0.8 at about 1 MHz.
However, the parameters of twisted
coil transformers are difficult to control precisely. In addition, it may not
be easy to manufacture identical
twisted coil transformers in large
quantity with high quality control.
Much research effort has been focused on the use of printed planar
windings for inductor or transformers [2–10]. The use of printed planar
windings not only eliminates the
costly manual winding process in traditional transformers but, more importantly, makes it possible to manufacture inductors or transformers with
precise parameters in an automated
manner. In most of the literature [2–
9], magnetic substrates or materials
are still used as parts of the magnetic
core structures. An interesting attempt of printing two spiral windings
on the same surface of a PCB without using a magnetic core is reported
in [10]. In [10], an integral equation
analysis method for predicting the
parameters of the printed single-sided
PCB transformer is presented.
In the literature mentioned so far,
the planar inductors and transformers
are of low output power (typically
less than 2W). Except in [1,10], the
magnetic designs require the use of
10mm
Figure 2. Dimensions of Tr6.
magnetic cores in one form or another. In this article, we summarize
the recent developments of coreless
PCB transformer technology [11–
17]. The misunderstandings that PCB
transformers without magnetic cores
might have low coupling factor, low
voltage gain and high radiated EMI
problems are clarified. With the aid of
a high-frequency circuit model, the
basic characteristics and application
examples of coreless PCB transformers are described. In particular, a resonant technique has been incorporated
into the use of the proposed coreless
PCB transformers so as to achieve a
high voltage gain (to overcome the
apparent low magnetic coupling) and
take advantage of the leakage inductance (to turn the apparent disadvantage into an advantage). Optimal operating techniques for using coreless
printed-circuit-board (PCB) transformers under (1) minimum input power
conditions and (2) maximum energy
efficiency conditions are described.
Basic Structure and Equivalent
Circuit of Coreless PCB
Transformers
The basic structure of a
coreless PCB transformer is
very simple. Essentially,
transformer windings are
printed on a double-sided
PCB. An example of a
coreless PCB transformer
(right) is shown in Fig. 1, together with a core-based pulse
transformer (left). In order to
illustrate the characteristic of
coreless PCB transformers, a prototype shown in Fig. 2 and labeled as
transformer Tr6 is used as an example.
The width and height of the copper
track are 0.22mm and 0.025mm, respectively. The distance between adjacent tracks is about 0.28mm. The number of turns for the primary and secondary printed windings is 10.
The equivalent circuit of a coreless
PCB transformer is shown in Fig. 3,
where
R1 is the primary winding resistance,
R'2 is the secondary winding resistance referred to the primary,
RL is the resistive load,
Llk1 is the primary leakage inductance,
L'lk2 is the secondary leakage inductance referred to the primary,
LM1 is the primary mutual inductance,
C1 is the primary winding capacitance,
C'2 is the capacitance in the secondary winding referred to the primary,
C12 is the capacitance between primary and secondary windings, and
n is the turns ratio.
. . . continued on Page 6
Figure 3. Equivalent circuit of the PCB transformer with
a parallel capacitive/resistive load.
C'12
R1
C'1
L lk1
L'lk2
L M1
R'2
C'2
C'L
2
N RL
5
Coreless Printed Circuit
Board (PCB) Transformers
Coreless PCB Transformers … continued from Page 5
The no-load resonant frequency of
the equivalent circuit is given by
fo =
1
2π
Leq C eq
(1)
where Leq = L'lk2 + Llk1 LM1 and Ceq
= C'2 + C'12 . (Here C'2 includes the
load capacitance.) The parametric
values of Tr6 measured at 10MHz
are shown in the equivalent circuit in
Fig. 4.
It is important to note from (1)
that the no-load resonant frequency
can be changed by connecting an
external capacitor C2 across the secondary winding terminals. This feature enables the optimal operating
frequency to be chosen for a particular application. For example, if the
operating frequency of the coreless
PCB transformer is limited to
10MHz, connecting a capacitor C2 of
680pF gives Tr6 a resonant frequency to be approximately 9 MHz.
Figure 4. High-frequency Equivalent Circuit Model of Tr6.
3.5 pF
1.4 ohm
304 nH
304 nH
275 nH
6
1.4 ohm
Characteristics of Coreless PCB
Transformers
Based on the equivalent model,
the frequency response of Tr6 loaded
with a capacitor C2 of 680pF and a
dummy load of 2kΩ is shown in Fig.
5a and Fig. 5b. The voltage gain is the
ratio of the output voltage to the input voltage (V2/V1).
Observation of this typical frequency response leads to the following important points that can be considered to operate the coreless transformer in an optimal manner:
(i) As expected, it can be observed that
the voltage gain at low operating frequency (less than 200kHz) is very
low. As the frequency increases, the
voltage gain increases until it
reaches its maximum at the resonant
frequency.
(ii) It is interesting to note that the voltage gain of the coreless PCB transformer can exceed 1.0 in the high-frequency region. This dispels the misunderstanding that coreless PCB transformers have low voltage gain.
(iii) The voltage gain of the transformer
drops to zero beyond the resonant
frequency. Thus the useable frequency range should be below the
resonant frequency.
(iv) The operating frequency of the
coreless transformer should be near
but below the resonant frequency. This
is the high-frequency end of the
useable operating range where the
magnetizing reactance is large. Otherwise, the equivalent behaves like a
short circuit at low-frequencies.
(v) Near the resonance region (just below the resonant frequency), the
– Fundamental Characteristics
and Application Potential
6
5.5
5
Measured
4.5
4
Calculated
3.5
Gain
voltage gain is
higher than the
rest of the operating range. This is
the “partial resonance” region
with high gain and
small phase shift.
One can take advantage of this
high-frequency
and high-gain region for various
applications. For
Tr6, the partial
resonance region
is in the range of
6 MHz –8.5MHz.
3
2.5
2
1.5
1
0.5
0
0.00E+00
2.00E+06
4.00E+06
6.00E+06
8.00E+06
1.00E+07
1.20E+07
1.40E+07
1.60E+07
1.80E+07
2.00E+07
Frequency / Hz
Figure 5a. Predicted and measured voltage gain versus operating frequency of Tr6.
Transformers for Signal Transfer
and Power Transfer
Maximum-Impedance Frequency
for Signal Transfer
Transformers are often used to
transfer signals with minimum power
involved. One example is the gate
drive circuit for power electronic devices such as power mosfets and insulated gate bipolar transistors (IGBTs).
The gate drive circuit of the power
electronic devices requires the gating
signal to be transferred to the gate with
a small amount of power involved. In
. . . continued on Page 8
Phase Shift (Vs leads Vp) / Degree
Figure 5b. Predicted and measured phase shift versus operating frequency of Tr6.
180
160
140
120
Measured
100
Calculated
80
60
40
20
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
0.00E+00 2.00E+06 4.00E+06 6.00E+06 8.00E+06 1.00E+07 1.20E+07 1.40E+07 1.60E+07 1.80E+07 2.00E+07
Frequency / Hz
7
36
m
m
400
Input Impedance / Ohm
350
Maximum-impedance
Secondary
Figure 7. Dimensions of the Transformer Tr9.
300
250
ment of the transformer for signal
transfer applications.
200
150
Maximum-Efficiency Frequency for
Power Transfer
100
50
0
0.00E+00 2.00E+06 4.00E+06 6.00E+06 8.00E+06 1.00E+07 1.20E+07 1.40E+07 1.60E+07 1.80E+07 2.00E+07
Frequency / Hz
Figure 6. Predicted (solid-line) and measured (dotted) input impedance
versus operating frequency of Tr6.
Coreless PCB Transformers … continued from Page 7
order to minimize the input power of
the transformer, one can consider the
input impedance characteristic. Based
on the transformer circuit model, the
input impedance of Tr6 can be determined and is shown in Fig. 6. Observation of these plots leads to the following important points:
1. The magnitude of the input impedance peaks at a frequency (termed
“maximum-impedance frequency”)
which is within the useable frequency
range and is slightly below the resonant frequency. For Tr6, this frequency
is about 8 MHz and the impedance is
about 150Ω.
2. The voltage gain at this “maximum-impedance frequency” is high
(about 1.8). That is, the signal can be
enlarged. The use of the partial-resonance technique overcomes the supposed low-gain problem and can make
the voltage gain greater than unity.
3. Operating the coreless PCB
transformer at or near this frequency
would minimize the power require8
Primary
Coreless PCB transformers can
be used as power transformers for
power transfer. Figure 7 shows a prototype (labeled as Tr9) that has been
tested for use in a 94W DC-DC power
converter [15]. Analysis of the energy
efficiency of the equivalent circuit for
various resistive loads indicates that
the coreless PCB transformers can
have a wide frequency range within
which a high energy efficiency exceeding 90% can be achieved. A plot
of the energy efficiency for Tr9 is
shown in Fig. 8. Because the power
consumption of the electronics driving the primary winding increases
with operating frequency, the optimal
operating frequency should be chosen
at the low-frequency end of the highefficiency region and should be below the resonant frequency of the
transformer circuit.
Electromagnetic Field
One common misunderstanding
about coreless transformers is that
there will be a serious radiated EMI
problem. For a loop antenna, the radiation is primarily perpendicular to
the x-y plane, i.e. θ =π/2. The intrinsic impedance η is 120π or 377Ω in
free space. If the operating frequency
Efficiency Versus Frequency
100%
90%
80%
Efficiency
70%
60%
High Efficiency Region
50%
40%
RL=50
RL=100
RL=200
30%
20%
10%
0%
0E+00 1E+06 2E+06 3E+06 4E+06 5E+06 6E+06 7E+06 8E+06 9E+06 1E+07
Frequency
Figure 8. Efficiency of the PCB transformer using FPC sheet with Cr = 390pF and various resistive loads, RL.
is 8MHz, the wavelength λ of the radiated signal is
λ=
c
3 x 10 8
=
= 37 .5m (2)
fC 8 x 10 6
where fc is the operating (or carrier)
frequency.
The time-averaged radiated
power (P) of a loop antenna is
 afc 
P = 160 π I  
 c
6 2
o
4
(3)
The radiated power depends on
(i) the current Io (or power of the operation), (ii) the dimension (radius a)
of the structure and (iii) the operating frequency fc. The radiated power
drastically increases with increasing
frequency and the dimension of the
radiating structure. According to antenna theory, a good loop radiator
should have a radius that is in the order of magntiude close to that of the
wavelength of the radiated signal. For
the transformer TR6, the radius of the
outermost loop is 0.005m. This radius
is only 0.13x10-3 of the wavelength λ
(37.5m). The term (a/λ)4 is in the order
of 10-16. For a current Io = 1A, the radiated power of a single loop antenna with
–11
a radius of 5mm is P = 4.86 x 10 W.
Therefore, the averaged radiated
power of a single loop with a radius of
5mm is negligible. Although the
coreless PCB transformer has 10 turns,
the radiated power involved and its radiated EMI effects are still too small
to be a concern. Therefore, the calculation indicates that the transformer
TR6 is an extremely poor transmitting
antenna as far as far-field radiation is
concerned. By the reciprocity theorem,
a poor transmitter is
also a poor receiver Figure 9. 3-D Field plot of coreless PCB transformer Tr6.
for a signal of a certain wavelength.
The 3-D field plot
of Tr6 excited at
8MHz is shown in
Fig. 9. The magnetic flux essentially concentrates
within and near
the structure of the
transformer.
. . . continued on Page 10
9
Figure 10. Modulated gate drive circuit using coreless PCB transformer.
5 ohm
1.1mH
3
2
1
2
0.1uF
3
1N4148
1uF
680pF
1N4148
330pF
1uF
1N4148
3
2 5
6
3.9k
2SC2120
7 4 8 TLC
555
6
3
2
1
1N4148
6.8k
APT5040
1uF
4
2SB561
1N4148
Buffer Module
Coreless PCB Transformers … continued from Page 9
Some Application Examples
Example 1 – Transformer Isolated Gate Drive Circuit with a Wide
Frequency Range
Isolation is often required between
the gate drive circuits and the power
electronic circuits so that the
low-voltage control electronic circuits are electrically
isolated from the power circuits. Aiming at (i) minimizing the input current requirement and (ii) providing a
wide range of switching frequency, the isolated gate
drive circuit and a test circuit
with a resistive-inductive
load (5Ω and 1.1mH) are
Figure 11a. Measured input (Vin) and
output (Vgs) signals of the gate drive
shown in Fig. 10. The power
circuit at fsw = 1 Hz.
MOSFET driven by the proposed gate drive is APT5040,
which has voltage and curFigure 11b. Measured input (upper:
rent ratings of 500V and 16A
Vin 10V/div.), carrier (middle: Vc 25V/div.)
and output (Vgs) signals of the gate drive
respectively. A capacitor of
circuit at fsw = 300 kHz.
680pF is connected across
the secondary winding so that
the resonant frequency of Tr6
will be set at about 9.1 MHz.
The large stabilizing capacitor of 1µF and the DC blocking capacitor of 0.1µF in the
secondary circuit will not significantly affect the frequency characteristic of the
transformer because they are
10
in series with a diode (1N4148)
which has typical capacitance of only
a few pico-Farads. A voltage-doubler
is included in the secondary circuit in
order to boost the gate drive voltage.
The carrier frequency fc (i.e. the operating frequency) is set at 8 MHz
which is the “maximum-impedance
frequency” of Tr6. The output signal
of the gate drive (i.e. the gate-source
voltage Vgs of the power MOSFET)
is controlled by the input signal Vin of
the gate drive in the modulation/demodulation process. Thus, the frequency of Vin determines the switching frequency (f sw ) of the power
MOSFET.
Figure 11a and Fig. 11b show the
waveforms of the input gating signal
and the output gate drive signal for
the power device at 1 Hz and 300kHz,
respectively. The carrier signal of
8MHz is also shown in Fig. 11b. The
input current of the entire gate drive
circuit versus operating frequency is
shown in Fig. 12. The minimum input current occurs at the maximumimpedance frequency as predicted. A
photograph of the actual test circuit
is shown in Fig. 13. The magnetic
field of the circuit has been scanned
by a Precision EMC scanner and is
shown in Fig. 14. Most of the EMI
emission comes from the upper lefthand region of the PCB (labeled as
region ‘T’). This area contains the
copper tracks that form part of the
S. C. Tang
power circuit. Thus, the major source
of EMI emission is the conducting
path of the power circuit (upper righthand side of the PCB) rather than the
coreless PCB transformer. Even the
gate drive circuit on the primary side
(region ‘P’) and the gate drive circuit
on the secondary side (region ‘S’)
have higher EMI emission than the
coreless PCB transformer (enclosed
in the square box). The EMI emission
from the coreless PCB transformer is
relatively small compared with that
from the power circuit and other electronic circuits in the entire circuit.
Unlike the power tracks and the gate
drive electronics where sharp voltage
and current transients occur, the
coreless transformer has some filtering effects and has no sharp rising and
falling voltage and current edges.
H. Chung
Figure 13. Photograph of the
top side of the PCB.
(Coreless PCB transformer is
enclosed by the square box.)
P
Figure 14. EMI from PCB with
both the gate drive circuit and
the power circuit turned on.
Frequency range: 30MHz to
300MHz.
T
▲
S. Y. (Ron) Hui
▼
▲
. . . continued on Page 12
S
Figure 12. Measured input current of the gate drive circuit versus
carrier frequency fc under the condition of duty cycle of 1.0
(the worst-case situation).
Supply Current / mA
240
220
200
180
160
140
120
100
80
60
40
20
0
5.00E+06 6.00E+06 7.00E+06 8.00E+06 9.00E+06 1.00E+07 1.10E+07 1.10E+07
Frequency / Hz
11
10mm
10mm
Figure 15. Two secondary windings (left) and
one primary winding (right) of the coreless
PCB transformer.
Gate Drive
Gate Drive
Figure 16. Coreless PCB Transformer with two
secondary outputs used in complementary gate
drive circuits.
Figure 17. Measured primary gating signal (V1), Drain-source
voltage of the two MOSFETs (Vds1 and Vds2) at 1MHz switching
operation. (V1: 10V/div.; Vds1 and Vds2: 20V/div.)
Coreless PCB Transformers … continued from Page 11
Although the coreless PCB transformer is placed fairly close to the
power circuit, its normal operation is
not affected by the EMI from the
power circuit [16].
Example 2 – Transformer with
Multiple Secondary Windings for
Totem-Pole Gate Drives
Multiple secondary windings can
also be constructed for coreless PCB
transformers. This can be done either
by printing the two secondary windings on the same side or printing them
in different layers in a multiple-layer
PCB. Figure 15 shows the winding dimensions of a coreless PCB transformer with two secondary windings.
This transformer has been used in two
totem-pole gate drive circuits (shown
in Fig. 16) which are commonly used
in power inverters. Figure 17 shows the
practical switching waveforms of
power devices at 1 MHz.
Example 3 – Isolation Amplifier
with 1MHz Bandwidth
Commercial isolation amplifiers
have frequency bandwidths up to
about 120kHz [18]. Because of the
absence of the core limitations,
coreless PCB transformers offer a
much higher bandwidth up to at least
1MHz. Figure 18 shows a typical isolation amplifier circuit. The power
transformer and the signal transformer are replaced by their coreless
counterparts T1 and T2, respectively
(Fig. 19). Figure 20 shows the voltage gain versus operating frequency
in this application example.
Example 4 – Transformers for
Maximum Power Transfer
Coreless PCB transformers have
been tested for power conversion applications with different rated power
outputs from 0.5W to 94W. The transformer Tr9 (Fig. 7) has been tested in
a low-profile switched mode power
. . . continued on Page 14
12
High Voltage
Isolation Barrier
POWER
+15V DC
Power Supply
Pulse
Generator
High Voltage
Isolation Barrier
INPUT
Power
Transfer
Transformer
Drive Circuit
OUTPUT
Low-Pass
Filter
Rectifier
and Filter
T1
Isolated
Output Signal
Isolated
Output Signal
Common
Demodulator
CR1
+VISO1 -VISO1
Power Return
Signal
Low-Pass
Filter
Power
CR2
Input Signal
Transformer
Drive Circuit
Modulator
Input Signal
Common
+VISO2 -V ISO2
Signal and
Power Transfer
Rectifier
and Filter
T2
Figure 18. Block diagram of an isolation amplifier.
mm
5
9.7
mm
56
5.8
Figure 19. (a) Shape of T1, (b) Shape of T2.
Gain versus Frequency
10
0
Gain (dB)
-10
-20
-30
Measured Gain
-40
Calculated Gain
-50
-60
-70
1.0E+01
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.0E+06
1.0E+07
Frequency (Hz)
Figure 20. Gain versus Frequency of the Isolation Amplifier Prototype.
13
+120V
References
SW1
IRF630
SW2
IRF630
S. Y. (Ron) Hui
S. C. Tang
H. Chung
14
[1] S.
Hayano,
Y.
Nakajima, H. Saotome,
and Y. Saito, “A New
Type High Frequency
Transformer”, IEEE
Transactions on Mag0.68 µ F
netics, vol. 27, no. 6,
November 1991, pp.
2µF
5205–5207.
Cr
RL
VO [2] W. Roshen, “Effect of
Finite Thickness of
Magnetic Substrate on
Planar Inductors”,
0.68µ F
IEEE Transactions on
Magnetics, vol. 26, no.
Figure 21. Circuit schematic of the half-bridge converter.
PCB Transformer
1, January 1990, pp.
with FPC Sheet
270–275.
[3] K. Yamaguchi, S.
Ohnuma, T. Imagawa,
J. Toriu, H. Matsuki,
and K. Murakami, “Characteristics of a
Coreless PCB Transformers … continued from Page 13
Thin Film Microtransformer with Circusupply with power output of 94W (Fig.
lar Spiral Coils”, IEEE Transactions on
Magnetics, vol. 29, no. 5, September
21). A maximum transformer effi1993, pp. 2232–2237.
ciency exceeding 95% (Fig. 22) and a
[4] M. Mino, T. Yachi, A. Tago, K.
maximum converter energy efficiency
Yanagisawa, and K. Sakakibara, “A
of about 84% have been achieved.
New Planar Microtransformer for Use in
Micro-Switching Converters”, IEEE
Conclusions
Transactions on Magnetics, vol. 28, no.
4, July 1992, pp. 1969–1973.
In this article, the characteristics
[5] C. H. Ahn and M. G. Allen,
and some application examples of
“Micromachined Planar Inductors on
coreless PCB transformers have been
Silicon Wafers for MEMS Applicadescribed. Several misunderstandings
tions”, IEEE Transactions on Industrial
Electronics, vol. 45, no. 6, December
of coreless PCB transformers have
1998, pp. 866–875.
been clarified. Without the limitations
[6] C. R. Sullivan and S. R. Sanders, “Deof the magnetic cores, coreless PCB
sign of Microfabricated Transformers
transformers offer better performance
and Inductors for High-Frequency
than their core-based counterparts in
Power Conversion”, IEEE Transactions
on Power Electronics, vol. 11, no. 2,
the high-frequency operating range.
1996, pp. 228–238.
Research into coreless PCB transform[7] C. R. Sullivan and S. R. Sanders, “Meaers is still in its early stage. It is envissured Performance of a High-Power-Denaged that coreless PCB transformers
sity Microfabricated Transformer in a
may find applications in many other
DC-DC Converter”, IEEE Technology
Update Series: Power Electronics and
areas. In particular, the advantages of
Applications II, IEEE Press, 1997, pp.
coreless PCB transformers make them
104–111
attractive in micro-circuits and in low- [8] Balakrishnan, W. Devereux Palmer, W.
profile applications in which stringent
Joines, and T. G. Wilson, “The Inducheight requirements have to be met.
tance of Planar Structures”, IEEE Power
Transformer Efficiency Vs. Switching Frequency
100%
95%
90%
85%
RL=30 Ohm
RL=50 Ohm
RL=100 Ohm
RL=200 Ohm
80%
75%
70%
65%
60%
55%
50%
1.0E+06
1.5E+06
2.0E+06
2.5E+06
3.0E+06
3.5E+06
4.0E+06
Switching Frequency (Hz)
Figure 22. Measured efficiency of the PCB transformer operated in the half-bridge power converter.
Electronics Specialists Conference Proceedings, 1993, pp. 912–921.
[9] W. G. Hurley, M. C. Duffy, S. O’Reilly,
and S. C. O’Mathuna, “Impedance Formulas for Planar Magnetic Structures
with Spiral Windings”, IEEE PESC Proceedings, 1997, pp. 627–633.
[10] I. Marinova, Y. Midorrikawa, S.
Hayano, and Y. Saito, “Thin Film Transformer and Its Analysis by Integral
Equation Method”, IEEE Transactions
on Magnetics, vol. 31, no. 4, July 1995,
pp. 2432–2437.
[11] S. Y. R. Hui, S. C. Tang, and H. Chung,
“Coreless Printed-Circuit-Board (PCB)
Transformers for Signal and Energy
Transfer”, IEE Electronics Letters, vol.
34, no. 11, May 1998, pp. 1052–1054.
[12] S. Y. R. Hui, S. C. Tang, and H. Chung
“Coreless PCB-Based Transformers for
Power MOSFET/IGBT Gate Drive Circuits”, IEEE Transactions on Power
Electronics, vol. 14, no. 3, May 1999,
pp. 422–430.
[13] S. C. Tang, S. Y. R. Hui, and H. Chung,
“Coreless Printed Circuit Board (PCB)
Transformers with Multiple Secondary
Windings for Complementary Gate
Drive Circuits”, IEEE Transactions on
Power Electronics, vol. 14, no. 3, May
1999, pp. 431–437.
[14] S. Y. R. Hui, S. C. Tang, and H. Chung,
“Optimal Operation of Coreless PCB
Transformer-Isolated Gate Drive Circuits
with Wide Switching Frequency Range,”
IEEE Transactions on Power Electronics,
vol. 14, no. 3, May 1999, pp. 506–514.
[15] S. C. Tang, S. Y. R. Hui, and H. Chung,
“Coreless Printed Circuit Board (PCB)
. . . continued on Page 47
S. Y. (Ron) Hui received the B.Sc. degree (Hons) at the University of Birmingham, U.K., in 1984, and the D.I.C. and Ph.D. degrees at Imperial College of Science,
Technology and Medicine, London, in 1987.
He was lecturer in power electronics at the University of Nottingham, U.K., in
1987–90. In 1990 he went to Australia for a lectureship at the University of Technology, Sydney, where he became senior lecturer in 1991. He later joined the University
of Sydney and was promoted to reader of electrical engineering and director of the
power electronics and drives research group in 1996. Presently he is chair professor of
electronic engineering and associate dean of the faculty of science and engineering at
the City University of Hong Kong.
S. C. Tang received the B. Eng. degree in electronic engineering (with first class
honors) from the City University of Hong Kong, Kowloon, Hong Kong, in 1997. He
is currently working towards the Ph. D. degree at the City University of Hong Kong.
His research interests include coreless PCB transformers, high-frequency magnetics, MOSFET/IGBT gate drive circuits, isolation amplifiers and switched-capacitor converters.
Henry Shu-hung Chung received the B.Eng. degree (with first class honors) in
electrical engineering from The Hong Kong Polytechnic University in 1991, and the
Ph.D. degree in 1994.
Since 1995 he has been with the City University of Hong Kong. He is currently
associate professor in the Department of Electronic Engineering. His research interests include time- and frequency-domain analysis of power electronic circuits, switchedcapacitor-based converters, random-switching techniques, digital audio amplifiers, and
soft-switching converters. He has authored two research book chapters, and over 110
technical papers including 50 refereed journal papers in the current research area.
Dr. Chung is presently associate editor of the IEEE Transactions on Circuits and
Systems—Part I: Fundamental Theory and Applications.
15
S. Gruhl
T. Rachidi
TEs
U
M
T
S
IP Network
BS
M. Link
M. Söllner
Real-Time Multimedia
Applications over 3rd
Generation Wireless
Networks
by S. Gruhl, T. Rachidi, A. Echihabi, M. Link, and M. Söllner
A
bstract—It is expected that in
3rd generation wireless networks in general, and in the Universal Mobile Telecommunications System (UMTS) in particular, complex
control and transport mechanisms
will influence the data communication. The wireless link quality varies
for a given application’s data flow,
while the application itself adapts to
the system and thus influences the
control mechanisms. In this paper,
we study the effects of such a dy16
namic system on the user-perceived
Quality of Service (QoS) for realtime multimedia applications over
UMTS, by means of simulating the
wireless link. The simulator comprises essential layer 2 and 3 protocol functionality of the UMTS Terrestrial Radio Access Network (UTRAN)
for terminal equipment (TE) and base
station (BS). It is used to demonstrate
in real-time the effects of 3rd generation wireless network access on IPbased multimedia applications.
UMTS
The Universal Mobile Telecommunication System (UMTS) will extend the services provided by current
second-generation systems (GSM,
PHS, IS-95, etc.) from simple circuitswitched voice telephony to complex
data services ranging from e-mail and
web-browsing to voice over packets,
media on demand, and video
conferencing [1]. Users will be able to
interact totally with their Wireless Information Devices to retrieve, store,
and process data anywhere, anytime
while being on the move. To this end,
UMTS will support packet-switched
data services for up to:
• 144 kbps for high speed mobile users
• 384 kbps for low speed mobile users
• 2 Mbps for portable/fixed users
Packet switched services use the system capacity more efficiently, and allow for user idle time and volume
charging policy. The statistical gain of
packet switching results from increased link utilization due to non-continuous bandwidth requirements from
applications. Such a mechanism is well
investigated in wireline networks
where medium capacity does not vary.
Major differences exist, however, between wireline and wireless networks,
because the radio link constitutes a
massive bottleneck:
• Power limitation, interference and
altering radio link conditions due to
mobile terminal position cause the
link capacity to change rapidly.
• Handoff calls lead to additional and
unpredictable load in a cell.
• High bit error rates (BER) are encountered in wireless communications. Forward error correction
(FEC) becomes important and retransmissions are more frequent than
in fixed networks. Consequently,
data rates are affected.
Once deployed, UMTS is expected
to interface seamlessly with the wide
variety of interactive, media-on-demand
and multimedia IP-based applications
developed originally for the Internet, like
the ITU standard H.323 “Packet Based
Multimedia Communications Systems” [12] as depicted in Fig. 1.
. . . continued on Page 18
Application
Audio/Video
Applications
Audio/Video
Codecs
RTC
H.323
Data
Applications
Terminal control and management
H.225.0
terminal
to gatekeeper
signaling
H.225.0
call
signaling
H.245
control
T.12x
RTP
Unreliable transport (e.g. UDP)
Reliable transport (e.g. TCP)
Network layer (e.g. IP)
T.123
Network
Link layer (e.g. UMTS)
Physical layer (e.g. UMTS)
Figure 1. Principal scheme of an Internet multimedia protocol stack, as used in the ITU
standard H.323 “Packet Based Multimedia Communications Systems” [12–17].
17
Relative Traffic
Data
250
200
Mobile
Voice
Fixed
Voice
150
100
50
Time
Data over
Circuits
Voice over
Packets
Figure 2. Estimated relative traffic mix.
Wireless Networks … continued from Page 17
The volume of data generated by
these applications is expected to
grow over-proportional in terms of
bandwidth consumption as depicted
in Fig. 2.
However, due to the above mentioned intrinsic characteristics of the
wireless link, it is a challenge to deliver
circuit-switched-like Quality of Service (QoS), such as bounded delay and
jitter, which are essential for multimedia and interactive applications. The
QoS needed for the broad variety of
data applications that will be available
over UMTS can be specified in terms
of several QoS parameters and classes.
Table 1 describes these classes.
It is critical to investigate UMTS
system performance from the perspectives of system efficiency and QoS
contract fulfillment. To this end, it is
essential to model the wireless subsystem in terms of its capacity and
transmission technique. Wideband
Code Division Multiple Access
(WCDMA) as the transmission technique for UMTS has the following
characteristics:
• CDMA is a spread spectrum technique developed for military antijam applications.
• Wide bandwidth supports high bit
Table 1. The four UMTS traffic classes defined by ITU-R [2–3].
18
Class
Number
Traffic Class
1
Conversational
2
Class Description
Example
Relevant
QoS Requirements
– Preserves time relation
between entities making up
the stream
– Conversational pattern based
on human perception
– Real-time
– Voice over IP
– Video conferencing
– Low jitter
– Low delay
Streaming
– Preserves time relation
between entities making up
the stream
– Real-time
– Real-time video
– Low jitter
3
Interactive
– Bounded response time
– Preserves the payload
content
– Web browsing
– Database retrieval
– Round trip
delay time
– Low BER
4
Background
– Preserves the payload
content
– Email
– File transfer
– Low BER
rates and helps to combat fading in
multi-path radio channels.
• Many users share the same radio
carrier.
• Each user is assigned a unique random code different from and approximately orthogonal to other codes.
• Quality degrades as the number of
users on a channel/carrier increases
(interference limited system).
WCDMA technology results in
soft-capacity behavior. In classical
schemes employing a combination of
Time Division Multiple Access and
Frequency Division Multiple Access
(TDMA/FDMA schemes), the total
capacity is static (see Fig. 3), and the
MultipleAccess
DS-CDMA (TD-CDMA)
Duplex
scheme
FDD (TDD)
Chip rate
3.84 MChip/s
Carrier
spacing
Flexible in the range 4.6–5.0 MHz
(200 kHz carrier raster)
Frequency
bands
Frame
length
10 ms; 15 time slots
Inter-BS
synchronization
No accurate synchronization needed
(synchronization needed)
Multi-rate/
Variable-rate
scheme
capacity
1920–1980 / 2110–2170 paired
(1900–1920 and 2010–2025 unpaired)
Variable-spreading factor + Multi-code
Spreading factor: 4–256 (1–16)
Channel
coding
scheme
Convolutional coding,
Turbo coding,
rate 1/2–1/3
Packet
Dual mode on common and
dedicated access channels
Table 2. UMTS Key Parameters (source 3GPP).
time
frequency
capacity
user #3
user #2
user #1
Interference
time
5 MHz
frequency
10 ms
Figure 3. Capacity in FDMA & TDMA (top)
versus W-CDMA (bottom).
QoS of an individual link is hardly
correlated to other carriers in the cell.
In CDMA the whole capacity is limited by the relative signal to noise ratio of the individual links (interference
limited system). Adaptive techniques,
e.g. power control and admission control are key in providing QoS for each
individual service.
This naturally imposes the need to
model physical layer behavior with
regard to individual services. Table 2
lists typical UMTS key parameters to be
taken into consideration in the model.
To address the specific requirements of services while achieving a
high spectral efficiency there are dif. . . continued on Page 20
19
Real-Time Multimedia
Applications over 3rd
Generation Wireless Networks
DTCH
Information data
Uplink
DCCH
2560
Information data
2560
CRC detection
96
96
CRC detection
CRC16
CRC16
Tail bit discard
2576
Tail8
112
Termination 12
Turbo Code R=1/3
7740
1st interleaving
7740
Viterbi decoding
R=1/3
360
1st interleaving
360
Radio Frame
segmentation
#1 1935
#2 1935
#3 1935
#4 1935
90
90
90
Rate matching
#1 2293
#2 2293
#3 2293
#4 2293
105 105 105
105
2293
107
2293
107
107
2293
90
2293
107
2nd interleaving
2400
2400
2400
2400
slot segmentation
1
240kbps DPDCH
2
1 2
…
…
Radio frame FN=4N
15 1
2
15 1 2
…
…
15 1
2
15 1 2
Radio frame FN=4N+1
…
…
15 1
2
15 1 2
Radio frame FN=4N+2
…
…
15
15
Radio frame FN=4N+3
Figure 4. Example of how two different services data/voice receive different physical layer processing.
Wireless Networks … continued from Page 19
ferent coding schemes applied to user
data as shown in Fig. 4.
For our investigations we concentrate on the UMTS terrestrial radio
access network (UTRAN), see Fig. 5.
Thus we explicitly model the UTRAN
part with its protocols, see Fig. 6. As
we work with the standard IP interface
we are able to include possible transit
networks in our investigation, by using existing networks as access networks to our demonstrator. These are
not modeled but actually coupled with
the real-time testbed. The detailed de20
scription of the testbed is out of the scope
of this paper, and is presented in [11].
UMTS Protocol Stack
The UMTS Radio Interface architecture is layered into a physical layer,
a data link layer and a network layer
(IP in this work). The data link layer
is divided into a Radio Link Control
(RLC) sublayer and a Medium Access
Control (MAC) sublayer. The Logical
Link Control (LLC) sublayer present in
many early UMTS proposals is not considered. It is expected that this sublayer
will be reduced to a Null-sublayer to
minimize protocol overhead and/or
will be merged with the PDCP Layer,
which is doing header compression.
Figure 5 shows protocol termination
for UMTS dedicated channel (DCH).
The following is a summary of the
main services and functions of Layer
1 and Layer 2 [4–6] that have been
RLC Sublayer Services:
• Transparent data transfer
• Acknowledged/unacknowledged
data transfer
• QoS settings
RLC Sublayer Functions:
• User data transfer
• Segmentation and reassembly
Application Services
Radio Access Bearer Services
TE
TAF
UE
MT
NodeB
UU
UE: User Equipment
MT: Mobile Termination
CN
RNC
Transit
Network
Terminating
Network
TE
IU
UTRAN
TE: Terminal Equipment
CN: Core Network
TAF: Terminal Adaption Function
Figure 5. Logical network architecture.
considered in the system:
Physical Layer Services:
• Information transfer services to higher
layers though Transport Channels
Physical Layer Functions:
• Error Detection and FEC on transport channels
• Multiplexing and de-multiplexing of
transport-channels/coded-transport
composite channels
• Synchronization
• Measurements and indication to
higher layers
MAC Sublayer Services:
• Data transfer
• Radio resources and MAC parameters reallocation
• Measurements reporting
MAC Sublayer Functions:
• MAC-scheduling and selection of an
appropriate transport format.
• Multiplexing/de-multiplexing of
higher layer PDUs into/from transport frames delivered to/from the
physical layer
• Traffic volume monitoring and reporting to RRM
• Padding
• In-sequence/out-of-sequence delivery of higher layer PDU
• ARQ—backward error correction
and flow control
UMTS provides besides other services a reliable RLC mode to be used
RLC
RLC
MAC
MAC
PHY
UE
PHY
BS
SRNC
Figure 6. Our model for the protocol in the UTRAN.
by non-real-time or interactive applications, based on FEC using various
channel coding schemes, radio blocks.
As can be seen, most UMTS layer
1 and 2 connectionless services and
functions have been considered. Functions for connection establishment on
the other hand have been ignored. This
assumption is valid for the scope of our
. . . continued on Page 22
21
Wireless Networks … continued from Page 21
project, as we are only interested in the
dynamic system behavior of an established link.
Control Loops
Stefan Gruhl
Tajje-eddine Rachidi
We have identified a set of challenging questions pertaining to wireless network performance in general
and to UMTS in particular, which we
address through the real-time testbed.
These questions are:
• How successful does a certain QoS
enabling technology such as UMTS
perform with a given application?
• What will user-perceived QoS be
like over a future wireless link?
• What are the traffic arrival characteristics of a certain type of future service, e.g., a video real-time session?
To illustrate what we consider as
protocol performance in this context,
Michael Link
we reference some studies of dynamic
TCP/IP behavior and its performance
over erroneous/slow links. TCP has
TCP-flow-control as an adaptation
mechanism for network congestion
situations. It acts on packet loss and
adapts its sending rate. For lossy links,
as experienced in wireless transmission, this mechanism can show unexpected behavior and perform poorly
[7–10]. We view these investigations
as one example of undesired control
loop interaction in a multi-protocollayer wireless environment. We are interested in control loops in general, as
e.g. also found in bandwidth adaptation methods in a scalable video codec.
Our approach also allows us to address
TCP performance investigations, but is
not restricted to this.
In the worst case we expect to find
oscillation effects that arise due to the
various dynamic controls
that are applied simultaneously by higher and
lower level protocols. These
mechanisms are found in
lower layers to overcome
lossy and variable capacity
links, and in higher layers
specifically to adapt to changing network capacity due to
congestion situations.
Michael Söllner
Stefan Gruhl received the masters in computer science in 1998 from the Friedrich Alexander University of Erlangen-Nürnberg. He is
currently participating in a joint research program between the Department of Computer Architecture and Performance Evaluation Institute of
the Friedrich Alexander University and the Global Wireless Systems Research Group at Bell Labs, Lucent Technologies. His research interest
is quality of service for packetized data for cellular wireless systems, particularly GPRS and UMTS.
Tajje-eddine Rachidi is associate professor of computer science at Alakhawayn University in Ifrane, Morocco. He received his first
degree from the Ecole Nationale Supérieure d’Informatique et de Mathématiques Appliquées de Grenoble (ENSIMAG), France, in 1989 specializing in real-time systems, and earned the Ph.D. degree from Essex University, U.K., in 1995. His research interests include 3rd generation
wireless networks and computer vision. He consults for various local companies in Internet/Intranet and database technologies. He is cofounder of CoreSoft: a software company developing intelligent components.
Michael Link received the diploma in electrical engineering from University Erlangen-Nürnberg, Germany, in 1994. From 1994 to 1999
he worked as research assistant at the Telecommunications Laboratory, University Erlangen-Nürnberg. In September 1999 he joined the Network Technology Group at Lucent Technologies, Nürnberg. His research interests are in channel coding for the transmission of multimedia
data in packet switched networks, channel modeling, and wireless multimedia protocols, especially for UMTS.
Michael Söllner received the diploma in mathematics in 1979 and the Ph.D degree from the University of Bochum, Germany in 1982.
Since 1984 he has held various positions in communication technology in industry, entering mobile communications with Philips in 1990,
where he focused on traffic and protocol engineering for mobile radio systems, being also involved in ETSI GSM standardization. He is now
responsible for a Bell Labs wireless research group with Lucent Technologies in Nürnberg, Germany. His current main research interests are
radio system aspects of 3rd generation wireless services.
22
In particular,
we have looked at
adaptive video
Client
Client
codecs on top of
the Real-time
TEs
Transport Protocol (RTP), which
run their independent control loops.
These interact
with other adapIP Network
tive control loops
from a wireless
network, in a way
comparable to the
TCP phenomBS
enon. There can
Server
be many control
loops, e.g. power
Server
control to adjust
the transmit power
on the radio link,
Figure 7: Standard Client/Server IP applications run through the UMTS protocol stack (red).
which affects error rates or control performed by the abled system. As we offer a real-time
Radio Resource Manager (RRM) on real-application interface, these effects
Resource Allocation. These interac- will be accessible for measurements.
tions, if not investigated and under- Furthermore, our system will allow demstood, can hinder the many benefits onstrating user perceived Quality of Serexpected from future wireless commu- vice over a simulated UMTS network.
For many higher layer protocols
nications networks.
and applications we lack the full deControl Loops and QoS
scription of internal control mechaFuture packet switched networks nisms, but often we find them as
will have to incorporate QoS enabling implemented applications. Most applitechniques to address specific applica- cations today communicate via IP traftion requirements. Imagine a guaran- fic. We use this transparent standard
teed bandwidth link with a low error IP-interface to transport application
data seamlessly in and out of our real
rate. Then you will find most of the
TCP-flow control problems to be soft- time simulation of a third generation
network. Thus standard IP-based apened to a large degree. How does this
work for other control loops? What are plications such as FTP, web browsing,
the QoS requirements that should be video applications or Microsoft
satisfied? How sensitive is this ap- NetmeetingTM can be simulated conproach to wireless intrinsic link varia- currently over the simulated UMTS
tion or actions like a handover to an- protocol stack and radio link (see Fig.
7). Our approach links existing appliother BS?
cations during run-time with our proWith our approach we will be able
to investigate the benefits of a QoS en- totype implementation of a UMTS
U
M
T
S
. . . continued on Page 24
23
Wireless Networks … continued from Page 23
protocol stack and with our PHY-layer
simulator. Thus we can run our investigations without the need to model the
application/higher layer part. By using
the real application we do not need any
traffic models assumptions, but use the
real dynamic behavior—including user
interaction—for our investigations.
Although there are QoS protocols
for IP networks, such as the Resource
Reservation Protocol (RSVP), these
QoS negotiation protocols are rarely
found in present applications. Therefore we have developed the concept of
individually assigned QoS for individual flows. A flow is distinguished
by its sending/receiving port number.
This allows us to do investigations
with a simulation of QoS enabled networks. The QoS requirements are for
example for reliability, delay, jitter, and
guaranteed bandwidth.
The main advantage of an on-line
simulation system is the possibility to
demonstrate the user-perceived quality of service. We can investigate the
effects of the various control mechanisms, altered radio conditions or a
congestion situation in a cell.
Conclusions
Quality of Service will be highly
important to enable new real-time
multimedia services for 3rd generation
mobile networks. Therefore it is important to investigate and understand
the influence of all protocol layers
from the physical link to the application. Therefore we have designed a
real-time testbed for performance as-
sessment of IP-based packet switched
and emulated circuit switched multimedia applications over UMTS. Our
proposed architecture allows concurrent access for an arbitrary number of
application-flows, while we provide a
QoS understanding on a per-flow basis even for non-QoS aware applications. This specifically allows investigating user-perceived QoS of today’s
multimedia applications over a simulated wireless link.
Starting from existing investigations on the performance of TCP over
a wireless link we broaden the field of
investigations to other higher layer
control loops such as those found in
adaptive RTP-based video applications, and combine them with simulated third generation wireless specific
RRM functionality and wireless lower
layer protocols.
Acknowledgements
We would like to thank Dr. Urs Bernhard and
Dr. Jens Mueckenheim for their kind support on all
areas of UMTS.
References
[1] General UMTS information, as found in
http://www.3gpp.org/
[2] O. Lataoui, T. Rachidi, L. G. Samuel, S.
Gruhl, and Ran Hong Yang, “A QoS Management Architecture in Packet Switched
Mobile Systems”, submitted to
INTEROP’00, IEEE, 2000.
[3] Technical Specification Group Services and
System Aspects, QoS Concept, Technical
Report 3G TR 23.907 version 1.1.0., 1999.
[4] C. Robool, P. Beming, J. Lundsjo, and M.
Johansson, “A Proposal for an RLC/MAC
Protocol for Wideband CDMA Capable of
Handling Real-Time and Non Real-Time
Services”, VTC’98, pp. 107–111.
. . . continued on Page 47
24
NEW ARTICLES
The IEEE Circuits and Systems Society Newsletter will become the
IEEE Circuits and Systems Society Magazine in January, 2001.
Style Considerations
1) Articles are readable by the entire CAS membership.
2) Articles are about eight published pages in length. We can, however, accommodate longer or shorter items if the situation seems
appropriate.
3) Articles communicate primarily by graphs, diagrams, and pictures.
Many authors have begun the inevitable transition to color, as may
be seen in back issues of the Newsletter, available at www.nd.edu/
~stjoseph/newscas/. In issue layout, the editors often build upon
the colors chosen by the authors.
4) Equations are to be used sparingly, except for special situations.
When equations are present, they may receive special graphical
design treatment.*
Submission Information
1) File format for diagrams, figures, graphs, and photos is .eps format. If another
format is needed, permission should be obtained from the editor at
sain.1@nd.edu. Such files should be provided separately from the text. If an
embedded document is submitted, say for ease of review, then accompanying text and separate .eps files should also be provided.
2) Abstracts, or complete papers, are submitted to the Features Co-Editors, who
will review them to determine if final papers will be a good fit. All papers are
subject to review and requests for revision.
Features Editors
Guanrong Chen
Department of Electronic Engr.
City University of Hong Kong
Hong Kong, P. R. China
(on leave from U. Houston)
Phone: (852) 2788– 7922
Fax: (852) 2788– 7791
E-mail: gchen@ee.cityu.edu.hk
Rui J. P. de Figueiredo
Department of Electrical
and Computer Engineering
University of California, Irvine
Irvine, CA, USA 92697–2625
Phone: (949) 824–7043
Fax: (949) 824–2321
E-mail: rui@uci.edu
* Note that December 1999 is an exception to the equation restriction.
Future exceptions are likely to be rare.
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IEEE CAS FELLOW
PROFILES 2000
Weiping Li
For contributions to image and video coding algorithms, standards, and implementations.
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Weiping
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Li
Weiping Li received the B.S. degree
from the University of Science and Technology of China (USTC) in 1982, and the M.S.
and Ph.D. degrees from Stanford University
in 1983 and 1988, respectively, all in electrical engineering. In 1987, he joined the faculty at Lehigh University, where he is professor in the Department of Electrical Engineering and Computer Science. Since 1998,
he has taken a leave from Lehigh University
to work on network streaming video in Silicon Valley, California.
Weiping Li is currently editor-in-chief of
the IEEE Transactions on Circuits and Systems for Video Technology. He served as associate editor of the same journal from 1995
to 1999. He was one of the guest editors for
a special issue of the IEEE Proceedings on
image and video compression in February,
1995. In 1998–1999, he served as past-chair,
and from 1996–1998, chair of the Technical
Committee on Visual Signal Processing and
Communications of the IEEE Circuits and
Systems Society. He is program chair of the
MPEG-4 Workshop and Exhibition. He was
co-chair in 1999 and chair in 1997 of the
Technical Track on Multimedia and Communications at the IEEE International Symposium on Circuits and Systems. He served as
chair of the Best Student Paper Award Committee for the 1999 SPIE Visual Communications and Image Processing Conference.
From 1997 to 1998, he served as chair of the
working group on reaffirmation of IEEE Standard 1180 (Specifications for the Implementation of 8X8 Inverse Discrete Cosine Transform). Since 1995, he has been a member of
the Moving Picture Experts Group (MPEG) of
the International Standard Organization (ISO).
Weiping Li received the Spira Award for
Excellence in Teaching in 1992 at Lehigh
University and the Guo Mo-Ruo Prize for
Outstanding Student in 1980 at University of
Science and Technology of China.
Norbert J. Fliege
For contributions to analog and digital signal processing, and to engineering education.
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Norbert J.
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Fliege
26
Norbert J. Fliege received the Dipl.-Ing.
degree and the Dr.-Ing. degree in 1971, both
from the University of Karlsruhe, Germany.
Since 1978, he has been associate professor
at the same university. In 1980, he was visiting professor at ESIEE in Paris. From 1982
to 1996, he was full professor and head of the
Telecommunication Institute at Hamburg University of Technology in Hamburg, Germany.
Since 1996, he has been full professor of electrical engineering and computer technology at
the University of Mannheim, Germany.
Since 1968, Dr. Fliege has been engaged
in research work in such fields as active filters, digital filters, communication circuits
and software, digital audio, and multirate digi-
tal signal processing. In addition, he served as
department chairman and head of a research
center. He has also founded a company providing telecommunication equipment.
Dr. Fliege has published approximately
one hundred papers, most of them in international magazines and conference proceedings,
and four books, one of them with the title
Multirate Digital Signal Processing, John
Wiley and Sons, 1994. Dr. Fliege is a senior
member of IEEE, a member of EURASIP,
and a member of VDE (Germany). He has received several national and international
awards. In 1997, he was given the honorary
doctorate from the University of Rostock,
Germany.
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CIRCUITS AND SYSTEMS
SOCIETY MEMBERS
Henry Samueli
For contributions to VLSI architectures and realizations for
high-bit rate digital communication systems.
Henry Samueli was born in Buffalo,
New York, on September 20, 1954. He received the B.S., M.S., and Ph.D. degrees
in electrical engineering from the University of California, Los Angeles (UCLA) in
1975, 1976, and 1980, respectively.
From 1980 to 1985 he was with TRW,
Inc., Redondo Beach, California, where he
was section manager in the Digital Processing Laboratory of the Electronics and
Technology Division. His group was involved in the hardware design and development of military satellite and digital radio communication systems. From 1980 to
1985 he was also part-time instructor in the
Electrical Engineering Department at
UCLA. In 1985 he joined UCLA full-time
and is currently professor in the Electrical
Engineering Department. His research interests are in the areas of digital signal processing, communications systems engineering, and CMOS integrated circuit design for applications in high-speed data
transmission systems. In 1988 he co-
founded PairGain Technologies, Inc.,
Tustin, California, a telecommunications
equipment manufacturer; and in 1991 he
co-founded Broadcom Corporation,
Irvine, California, an integrated circuit
supplier to the broadband communications
industry. Since 1995 he has been on leave
of absence from UCLA while serving fulltime as chief technical officer of Broadcom
where he is responsible for all research and
development activities for the company.
Dr. Samueli was the recipient of the
1988/1989 TRW Excellence in Teaching
Award of the UCLA School of Engineering and Applied Science, the Meritorious
Paper Award of the 1991 Government
Microcircuit Applications Conference, the
1995 Best Paper Award from the IEEE
Journal of Solid-State Circuits, and the
Jack Kilby Best Paper Award from the
2000 IEEE International Solid-State Circuits Conference. He received the 1999
Engineer of the Year Award from the Orange County Section of the IEEE.
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Samueli
Peter Feldmann
For contributions to the analysis and simulation of electronic circuits.
Peter Feldmann was born in Timisoara, Romania. He began his university
studies at the Polytechnic Institute in
Bucharest, Romania; and after two years he
continued at the Technion, in Haifa, Israel.
There he received the B.Sc. degree, summa
cum laude, in computer engineering, in
1983, and the M.Sc. degree in electrical
engineering in 1987. From 1985 through
1987 he worked for Zoran Microelectronics in Haifa, Israel, on the design of digi-
tal signal processors. Feldmann continued
his graduate studies at Carnegie Mellon in
Pittsburgh, Pennsylvania, and obtained the
Ph.D. degree in 1991. Currently, he is a
distinguished member of the technical
staff at Bell Labs in Murray Hill, New Jersey. In 1995 he was an adjunct professor
at Columbia University in New York. His
main research interests are simulation, analysis and design of electronic circuits and communication systems.
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Peter
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Feldmann
27
Fuzzy Systems Technology:
A Brief Overview
A
bstract—In this article, the basic
concepts of fuzzy sets and fuzzy
logic are first introduced. The results
of industrial and biomedical applications of fuzzy systems technology in the
areas of image/signal processing, automation, and control are then briefly
reviewed. Finally, a summary of latest
theoretical advances on fuzzy control,
fuzzy modeling and fuzzy approximation is provided.
Recognized by the IEEE as one of
the emerging information processing
technologies, fuzzy systems technology has achieved, especially in the last
several years, widespread applications
around the globe in many industries
and technical fields, ranging from control, automation, and AI to image/signal processing and pattern recognition.
The basis of the technology is a
fuzzy set that is an extension of the
Membership
1
Young
Figure 1. One possible description
of vague concept “young” by
classical sets.
Age (year)
0
35
classical set. In traditional set theory,
membership of an object belonging to
a set can only be one of the two values: 0 or 1. An object either completely
belongs to a set or does not at all. No
28
partial membership is allowed. Crisp
sets handle black-and-white concepts,
such as “chairs”, “ships”, and “trees”,
where little ambiguity exists. Nevertheless, in our daily lives, there exist
countless vague concepts that we humans can easily describe, understand
and communicate with each other; but
conventional mathematics, including
the set theory, fails to handle in a rational way.
The concept “young” is an example to the point. For any specific
person, age is precise. However, relating a particular age to “young” involves fuzziness and is sometimes difficult. What age is young and what age
is not? The nature of questions like this
is deterministic, not stochastic. A hypothetical crisp set “young” is given in
Fig. 1. A fundamental problem is the
abrupt change of the membership
value from 1 to 0 at a certain age (35
in this case), which means that a 34.9
years old person is completely young
whereas a 35.1 years old person is not
young at all. To address issues like this,
fuzzy set theory generalizes 0 and 1
membership values of a crisp set to a
membership function of a fuzzy set.
Using the theory, one relates an age to
“young” with a membership value
ranging from 0 to 1; 0 means no association at all, 1 indicates complete association, and any number in between
means partial association. One possible fuzzy set “young” is provided in
Fig. 2. One sees that every age is
“young” to a degree (equivalently, everyone is “young” to a certain extent).
by Hao Ying
Of course, no standard fuzzy set
“young” exists. People have different
views on the same (vague) concept.
Fuzzy sets can be used easily to accommodate this reality. Continue the
age example. Some people might think
age 50 is “young” with membership
value as high as 0.9 whereas others
might consider that 20 is “young” with
membership value merely 0.2. Different fuzzy sets can be used to represent
these different versions of “young.”
Not only do different people have different fuzzy sets for the same concept,
even for the same person, the fuzzy set
for “young” can be different when the
context in which age is addressed varies. For instance, a 40 years old president of a country would likely to be
regarded young whereas a 40 years old
athlete would not be considered young.
Two different fuzzy sets “young” are
needed to deal with the two situations.
In classical set theory, there are
binary logic operators AND (i.e., intersection), OR (i.e., union), and NOT
(i.e., complement). The corresponding
fuzzy logic operators exist in fuzzy
sets theory. Fuzzy logic AND and OR
operations are widely used in fuzzy
systems. Unlike the binary AND and
OR operators whose operations are
uniquely defined, their fuzzy counterparts are non-unique. Numerous fuzzy
logic AND operators and OR operators
have been proposed; some of them
purely from a mathematics point of
view. To a large extent, only Zadeh
fuzzy AND and OR operators are most
useful. Suppose that a specific age, say
30, is “young” (a fuzzy set) with a
membership value of 0.8 and is “old”
(another fuzzy set) with a membership
value of 0.3. Then, the membership
value for the age being “young and
Membership
1
Figure 2. One possible description
of vague concept “young” by
fuzzy sets.
Young
Age (year)
0
10
30
50
70
90
old” (a newly formed fuzzy set) is 0.3
if the Zadeh fuzzy AND operator is
used. The membership value for the
age being “young or old” (another
newly formed fuzzy set) is 0.8 if the
Zadeh fuzzy OR operator is utilized.
From these simple examples, one
sees that (1) fuzzy sets can practically,
quantitatively and flexibly represent
vague concepts, and (2) this representation is mathematically precise.
Fuzzy sets and fuzzy logic form
the foundations for fuzzy mathematics,
which may be viewed as an extension
of the traditional mathematics. The
new branches include fuzzy algebra,
. . . continued on Page 30
29
Fuzzy logic
operators
Input
variables
x1
x2
:
Fuzzy
inference
method
Fuzzy
rule base
Fuzzy sets
Fuzzification
Fuzzy
reasoning
Defuzzifier
Defuzzification
:
Output
variables
y1
y2
yN
xM
Figure 3. Structure of a typical rule-based MIMO fuzzy system, such as a fuzzy controller or a fuzzy model.
Fuzzy Systems Overview … continued from Page 29
fuzzy calculus, fuzzy differential equations, fuzzy graphs, fuzzy topology,
and fuzzy spaces, to name just a few.
The extension is often technically dif-
Fuzzy sets and fuzzy logic form
the foundations for fuzzy mathematics, which may be viewed as
an extension of the traditional
mathematics. The new branches
include fuzzy algebra, fuzzy calculus, fuzzy differential equations,
fuzzy graphs, fuzzy topology, and
fuzzy spaces, to name just a few.
The extension is often technically
difficult.
ficult. For instance, solving a fuzzy
quadratic algebraic equation ax2 + bx
+ c = 0 or fuzzy first-order differential
equation ax' + bx + c = 0, where a, b,
and c are fuzzy sets, is more challenging than their crisp counterparts. The
answers depend on the fuzzy sets a, b,
30
and c, and may not exist or be unique.
Although a vast volume of theoretical
results has been reported in the literature, the majority of them are pure
mathematics and have yet to find useful practical applications. Nevertheless, a small part of fuzzy mathematics has proved to be very useful for the
creation and development of fuzzy
systems technology.
Loosely speaking, any system that
uses fuzzy mathematics may be viewed
as a fuzzy system. More strictly, fuzzy
systems may be divided into two groups:
pure fuzzy systems that are developed
entirely on the basis of fuzzy mathematics, and hybrid fuzzy systems that
are constructed by a mixture of fuzzy
mathematics and non-fuzzy techniques. Even pure fuzzy systems only
use a small portion of the fuzzy mathematics available; this portion is also
mathematically quite simple and conceptually easy to understand. Most of
the (rule-based) pure fuzzy systems,
including all the fuzzy controllers and
fuzzy models, accomplish their objectives by periodically executing the following three steps: fuzzification, fuzzy
reasoning, and defuzzification. A typical MIMO (multiple-input multipleoutput) fuzzy system of this category
is depicted in Fig. 3.
ler, which is a typical rule-based fuzzy
system. We assume that the controller
is simple and only has two input variables and one output variable. To put
Regardless of the type, pure or hybrid, the role that fuzzy mathematics
plays in a fuzzy system can ultimately
be viewed as a practical, simple and intuitive way to incorporate nonlinear
characteristics/effects to the system so
that it can outperform its linear counterpart. Simply put, fuzzy systems are just
nonfuzzy systems with some intrinsic,
peculiar and advantageous nonlinear
features. More specifically, fuzzy systems are nonlinear systems with variable gains/coefficients constantly
changing with the input state of the
systems. It is these variable gains/coefficients that enable the fuzzy systems
to perform better, if properly designed.
We now graphically illustrate this
important point using a fuzzy control-
Simply put, fuzzy systems are just
nonfuzzy systems with some intrinsic,
peculiar and advantageous nonlinear
features.
the demonstration in the perspective of
fixed-gain systems, we first show a
constant gain (Fig. 4a) and the resulting output of a simple linear system
(Fig. 4b). Figures 5a and 5b give, re. . . continued on Page 32
(a)
(b)
8
6
Gain
4
2
0
-10
5
10
Output
5
0
5
Input 1
-5
0
-5
0
0 Input 2
-5
Input 2
-5
10
0
-5
-10
Input 1
5
5
10 -10
10 -10
Figure 4. (a) An example of constant gain of a simple linear system/controller; (b) the resulting system output.
(a)
(b)
2
Gain 1.75
1.5
1.25
2
1
0 Input 2
-4
-2
10
5
0
-5
-10
-10
10
5
0
-5
-1
0
Input 1
Output
2
4
-2
Input 1
Input 2
-5
0
5
10 -10
Figure 5. An example simple fuzzy system/controller: (a) its variable gain around the origin;
(b) its output in the entire input space.
31
(a)
Figure 6. Three more examples of nonlinear gain
variation characteristics. They are generated by
another simple fuzzy system/controller at three
different sets of parameter values.
1
0.75
Gain 0.5
0.25
0
-10
10
5
0
-5
Input 2
-5
0
Input 1
Fuzzy Systems Overview … continued from Page 31
5
10 -10
(b)
1
0.75
Gain 0.5
0.25
0
-10
10
5
0
-5
-5
0
Input 1
Input 2
5
10 -10
(c)
1
0.75
Gain 0.5
0.25
0
-10
10
5
0
-5
-5
0
Input 1
5
10 -10
32
Input 2
spectively, the variable gain for the
input state around the origin region and
the output of the fuzzy controller in the
entire input space. Clearly, the variable
gain causes the system output to be
nonlinear. It can be proved that the
gain variation leads to better performance of the fuzzy controller relative
to its linear counterpart, which is a linear PI (proportional-integral) controller. The more detailed coverage however is beyond the scope of this short
article [1]. Figures. 6a to 6c provide
more examples of nonlinear gain
variation characteristics, all of which
are inherently built into a different
fuzzy controller at three different parameter settings. By changing the parameter values, an infinite number of
different gain variations can be generated.
Many commercial products have
been produced by fuzzy systems technology, especially in the past 10 years
or so [3]. The technology has been
used to enhance the processing of digital images and signals. The results include the autofocus system for Canon
cameras, and the autofocus, autoexposure, and autozoom systems for
Minolta cameras. Fuzzy logic has also
made Sanyo and Canon camcorders
better by making their autofocus,
autoexposure, and auto-white-balancing systems more intelligent. Other
examples include the image stabilizer
for camcorders from Matsushita, and
TV sets made by Sanyo. In the latter
case, fuzzy inference was used to im-
Fuzzy Systems Technology:
A Brief Overview
prove the image quality. In addition,
fuzzy systems technology has improved the electrophotography process
of photocopying machines from
Canon and Ricoh, and boosted the
image quality of Sanyo copies by improving their toner supply control and
Matsushita copies by introducing more
precise autoexposure and toner control. Other successful applications include voice recognition, and handwritten language recognition.
Fuzzy control is the most successful and active branch of fuzzy systems
technology, in terms of both theoretical research and practical applications.
The primary thrust of this novel control paradigm, created in the early
1970s, is to utilize a human control
operator’s knowledge and experience
to intuitively construct controllers so
that the resulting controllers are able
to emulate human control behavior to
a certain extent. Compared to the traditional control paradigm, the advantages of fuzzy control paradigms are
twofold. First, a mathematical model
of the system to be controlled is not
required (an impossible assumption for
most, if not all, other modern control
methodologies); and (2) a satisfactory
nonlinear controller can often be developed empirically without complicated mathematics. The core value of
these advantages is the practicality,
leading to less system development
time and cost.
Industrial automation and commercial products have been successfully developed worldwide using fuzzy
control. And Japan has led the way. Its
success includes Hitachi’s automated
train operation for the Sendai subway
Industrial automation and
commercial products have been
successfully developed worldwide using fuzzy control. And
Japan has led the way. Its success includes Hitachi’s automated train operation for the
Sendai subway system in Japan
that has been in daily operation
since about 1987. The trains,
controlled by a fuzzy predictive
controller, consume less electric
energy, and ride more comfortably than the ones controlled by
the nonfuzzy controllers.
system in Japan that has been in daily
operation since about 1987. The trains,
controlled by a fuzzy predictive controller, consume less electric energy,
and ride more comfortably than the
ones controlled by nonfuzzy controllers. Another Hitachi product is the
group fuzzy control operation for elevators. The waiting time and idle
. . . continued on Page 34
33
Fuzzy Systems Overview … continued from Page 33
time of the elevators are reduced during the rush hour; and riding and stopping are smoother.
Fuzzy control started to be built
into consumer products around the
turn of the 1990s. Home electronics/
appliance products include fuzzy controlled rice cookers, vacuum cleaners,
A major application area has
been in the automotive industry, where most of the major
automobile manufacturers in
the U.S., Japan and Europe
have actively been pursuing
the concept. Fuzzy control has
been used to control the engine
system, automatic transmission
system, suspension system, antilock brake system, and climate
system. These systems are either regulated individually or
jointly to make the vehicles
better, more efficient and safer.
washing machines, and home climate
control systems. A major application
area has been in the automotive indus34
try, where most of the major automobile manufacturers in the U.S., Japan,
and Europe have actively been pursuing the concept. Fuzzy control has
been used to control the engine system,
automatic transmission system, suspension system, anti-lock brake system, and climate system. These systems are either regulated individually
or jointly to make the vehicles better,
more efficient and safer.
While fuzzy systems technology
has been applied to many different industries, its larger impact is expected
to be on the healthcare industry. At
present, however, the number of biomedical applications is relatively
small, partially due to the inherent
complexity and uncertainty of the systems as well as the risks involved. Biomedicine is much more an art than a
science in that human knowledge, experience and skills play a vital role in
the diagnosis and treatment of diseases. Biomedical systems are the
most difficult systems to control because they are intrinsically nonlinear,
time-varying and have time delay.
In the late 1980s, a real-time fuzzy
control drug delivery system was successfully developed and clinically
implemented to regulate blood pressure in postsurgical open-heart patients
at the Cardiac Surgical Intensive Care
Unit [2]. This is the world’s first realtime fuzzy control in medicine. Fuzzy
systems have also been applied to control of muscle immobility and hypertension during general anesthesia, assessment of cardiovascular dynamics
during ventricular assistance, diagnosis of artery lesions and coronary
stenosis, support for seriodiagnosis,
intelligent medical alarms, and
multineuron studies. Other successful
medical applications are the detection
of coronary artery disease, classification of tissue and structure in electrocardiograms, and classification of normal and cancerous tissues in brain
magnetic resonance images.
Fuzzy systems can be realized in
a number of different ways. In many
commercial products, they are embedded systems implemented via generalpurpose microcontrollers, such as
those made by Motorola, or via dedicated fuzzy logic/inference processors
that are special VLSI chips. They can
also be integrated with other hardware
components of the products. A number
of fuzzy system development software
packages are on the market to facilitate the development of fuzzy systems,
especially fuzzy controllers. They include MATLAB Fuzzy Logic
Toolbox TM, Mathematica Fuzzy
LogicTM, SieFuzzyTM, fuzzyTech TM,
TILShell TM, FIDE TM, RT/Fuzzy TM,
Fuzzy Knowledge Builder TM, and
Fuzz-CTM. These packages provide
friendly graphical user interfaces to
make the fuzzy system development
easier and more efficient. Better yet,
Fuzzy systems have also been applied to control of muscle immobility and hypertension during general
anesthesia, assessment of cardiovascular dynamics during ventricular assistance, diagnosis of artery
lesions and coronary stenosis, support for seriodiagnosis, intelligent
medical alarms, and multineuron
studies.
once a fuzzy system is completed and
needs to be deployed, some of the
packages can automatically generate
optimized assembly code, C code, or
microcontroller code to be directly
downloaded to the target hardware.
Theory of fuzzy systems has advanced significantly along with the
rapid success of the practical applications. Most fuzzy controllers are used
as black-box controllers in that their
internal mathematical structures are
unknown. Since the late 1980s, significant progress has been made to mathematically explore the structure of
various types of fuzzy controllers [1].
Fuzzy control has been related to PID
control, sliding mode control, adaptive
. . . continued on Page 36
Hao Ying is associate professor in the Department of Electrical and Computer
Engineering, Wayne State University, after leaving the faculty of the University of Texas
Medical Branch at Galveston. He is also advisory professor of Dong Hua University,
Shanghai, China. He received the B.S. and M.S. degrees in electrical engineering from
Dong Hua University in 1982 and 1984, respectively, and the Ph.D. degree in biomedical
engineering from the University of Alabama at Birmingham in 1990. He holds one
U.S. patent and has published one research monograph and 44 journal papers. He served
as program chair for a major international intelligent systems conference in 1994, was
publication chair for the 2000 IEEE International Conference on Fuzzy Systems, and
has been program committee member for many international conferences. He is guest
editor for three journals and has been invited to review papers for 24 journals, including six different IEEE Transactions.
35
Fuzzy modeling is a new modeling paradigm, and fuzzy models are
nonlinear dynamic models. Compared with the conventional blackbox modeling techniques that can
only utilize numerical data, the
uniqueness of a fuzzy modeling approach lies in its ability to utilize
both qualitative and quantitative information.... Qualitative information is human modeling expertise
and knowledge.... The expertise and
knowledge are actually nonlinear
structures of physical systems, and
the structures are represented in an
implicit and linguistic form instead
of an explicit and analytical form.
Fuzzy Systems Overview … continued from Page 35
control, relay control, etc. in conventional control, resulting in insightful
understanding of fuzzy control in the
context of classical control. The results
have also been used to analyze some
important aspects of fuzzy control systems, including system stability and
control performance, and to better design fuzzy controllers.
System modeling and system control are two closely related problems.
A common form of the system model
is a differential equation for continuous-time systems or a difference equation for discrete-time systems. Nonlinear systems are complex and, worse
36
yet, no general theory exists for modeling them. Different nonlinear system
modeling techniques have been developed, including the Volterra and
Wiener theories of nonlinear systems.
Such nonlinear system models are
called black-box models because they
only attempt to mimic a system’s input-output relationship with the measurement data and hence cannot provide any insight on internal structure
of the system. Nonlinear system modeling is complicated because there exist an infinitive number of possible
model structures. Correctly assuming
a nonlinear model structure is a very
hard problem.
Fuzzy modeling is a new modeling
paradigm, and fuzzy models are nonlinear dynamic models. Compared
with the conventional black-box modeling techniques that can only utilize
numerical data, the uniqueness of a
fuzzy modeling approach lies in its
ability to utilize both qualitative and
quantitative information. This advantage is practically important and even
crucial in many circumstances. Qualitative information is human modeling
expertise and knowledge, which are
captured and utilized in the form of
fuzzy sets, fuzzy logic and fuzzy rules.
The expertise and knowledge are actually nonlinear structures of physical
systems, and the structures are represented in an implicit and linguistic
form instead of an explicit and analytical form. Fuzzy models are often intuitive because fuzzy sets, fuzzy logic
and fuzzy rules are intuitive and meaningful. However, fuzzy models are not
as simple as those models that can be
expressed in mathematical formulas.
In general, fuzzy models are black-box
models. Nevertheless, under certain
conditions, analytical structure of
some fuzzy models can be derived.
When this is the case, the fuzzy mod-
els are no long black-boxes. Recent
theoretical analysis shows that some
fuzzy models are actually nonlinear
ARX (Auto Regressive with eXtra input) models with variable model parameters.
A system capable of uniformly approximating any continuous function
is called either a functional approximator or a universal approximator. The
issue of universal approximation is
crucial to fuzzy systems. In the context
of control, the question is whether a
fuzzy controller can always be constructed to uniformly approximate any
desired continuous, nonlinear control
solution with enough accuracy. For
modeling, the question is whether a
fuzzy model can always be established
which is capable of uniformly approximating any continuous, nonlinear
physical system arbitrarily well.
Recent theoretical work has led to
affirmative answers to these qualitative
questions. Furthermore, the latest theoretical progress has provided quantitative answers to the following issues:
(1) necessary and sufficient conditions
for universal approximation, and (2)
given a continuous function, how to
design a fuzzy system to uniformly approximate it with a required approximation accuracy. The establishment of
the necessary conditions has also provided insight on the strengths and limitations of fuzzy systems as functional
approximators. On one hand, even if
a required approximation accuracy is
very small, a small number of fuzzy
rules may suffice to uniformly approximate those continuous functions
that have a complicated formulation
but a relatively small number of extrema. On the other hand, a large number of fuzzy rules are necessary for
uniform approximation of continuous
functions that are simple but have a lot
of extrema (i.e., periodic functions).
The interested reader is referred to
[1] for an up-to-date, comprehensive,
and deep theoretical treatment of fuzzy
control, fuzzy modeling and fuzzy approximation.
References
[1] H. Ying, Fuzzy Control and Modeling:
Analytical Foundations and Applications,
IEEE Press, 2000.
[2] H. Ying, M. McEachern, D. Eddleman,
and L. C. Sheppard, “Fuzzy Control of
Mean Arterial Pressure in Postsurgical Patients with Sodium Nitroprusside Infusion”, IEEE Transactions on Biomedical
Engineering, 39:1060-1070, 1992.
[3] J. Yen, R. Langari, and L. A. Zadeh (eds.),
Industrial Applications of Fuzzy Logic
and Intelligent Systems, IEEE Press,
1995.
The issue of universal approximation is crucial to fuzzy systems. In
the context of control, the question
is whether a fuzzy controller can always be constructed to uniformly
approximate any desired continuous, nonlinear control solution with
enough accuracy. For modeling, the
question is whether a fuzzy model
can always be established which is
capable of uniformly approximating
any continuous, nonlinear physical
system arbitrarily well.
Recent theoretical work has led to
affirmative answers to these qualitative questions.
37
ty
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Awards Nominations 2001
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ci the CAS
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homepage
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Nominations should be submitted electronically to the 2001 Awards Chair, Bing Sheu, at b.wehner@ieee.org. Forms may also
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oc
Sheu c/o Barbara Wehner, 15 W. Marne Ave., P.O. Box 265, Beverly Shores, IN 46301–0265. Tel: (219) 871–0210; Fax: (219) 871–0211.
◊◊ Guillemin-Cauer Award ◊◊
◊◊ Industrial Pioneer Award ◊◊
Purpose: To honor a person or persons with outstanding and pioneering
contributions in developing academic and industrial research results into
industrial applications and/or commerical products.
The award is to be presented annually together with the other awards,
and given by the Awards Committee on the basis of quality, originality, and
significance of contribution. Prize: Plaque and a $500 cash award that will
be divided if there is more than one recipient.
◊◊ Education Award ◊◊
◊◊ Darlington Award ◊◊
Purpose: To honor a person with outstanding contributions to education in a field within the scope of the CAS Society as documented
by publications of textbooks, research supervision of graduate and
undergraduate students, development of short courses and participation in adult education. The award is based on general quality and
originality of contributions and continuity of effort. Anyone who is
a member of the CAS Society is eligible. Prize: Plaque and $500
check.
Purpose: To recognize the best paper bridging the gap between
theory and practice published in the IEEE Transactions on Circuits
and Systems. The award is based on general quality, originality, contributions, subject matter and timeliness. Anyone who is an author
of papers bridging the gap between theory and practice published
in the IEEE Transactions on Circuits and Systems during the two
calendar years preceding the award is eligible. Prize: Certificate
and $250 check for each author (maximum of $1,000 per award).
◊◊ CAD Transactions Best Paper Award ◊◊
◊◊ Technical Achievement Award ◊◊
Purpose: To honor a person with outstanding technical contributions over a period of years within the scope of the CAS Society as documented by publications (including patents). The
award is based on the general quality and originality of contributions and continuity of effort. Anyone who is a member of the
CAS Society is eligible. Prize: Plaque and $500 check.
Purpose: To recognize the best paper published in the IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems. The
award is based on general quality, originality, contributions, subject matter and timeliness. Anyone who is an author of a paper published in the
IEEE Transactions on Computer-Aided Design of Integrated Circuits and
Systems during the two calendar years preceding the award is eligible.
Prize: Certificate and $250 check for each author (maximum of $1,000
per award).
◊◊ Mac Van Valkenburg Award ◊◊
◊◊ VLSI Transactions Best Paper Award ◊◊
Purpose: To honor a person with outstanding technical
contributions in a field within the scope of the CAS Society and outstanding leadership in the field. The award is
based on quality and significance of contribution and continuity of technical leadership. Anyone who is a member
of the CAS Society is eligible. Prize: Plaque and $1,000
Check.
Purpose: To recognize the best paper published in the IEEE Transactions on
Circuits and Systems for Very Large Scale Integration (VLSI) Systems. The
award is based on general quality, originality, contributions, subject matter and
timeliness. Anyone who is an author of a paper published in the IEEE Transactions on Circuits and Systems for VLSI Systems during the two calendar years
preceding the award is eligible. Prize: Certificate and $250 check for each author (maximum of $1,000 per award).
◊◊ Chapter-of-the-Year Award ◊◊
◊◊ CSVT Transactions Best Paper Award ◊◊
Purpose: To recognize the CAS Society Chapter with
the best yearly activities. The award is based on best
yearly activities in the categories of Chapter-sponsored technical activities, increase in membership and
participation in BOG meetings. Anyone who is a
member of the CAS Society Chapters is eligible.
Prize: Certificates to Chapter Officers.
Purpose: To recognize the best paper published in the IEEE Transactions on Circuits and Systems for Video Technology. The award is based on general quality, originality, contributions, subject matter and timeliness. Anyone who is an author of papers published in the IEEE Transactions on Circuits and Systems for Video Technology during the two calendar years preceding the award is eligible. Prize: Certificate and $250 check for each author (maximum of $1,000 per award).
◊◊ Meritorious Service Award ◊◊
Purpose: To honor a person with outstanding
long-term service to the welfare of the CAS
Society. The award is based on dedication, effort and contributions. Anyone who is a member of the CAS Society is eligible. Prize:
Plaque and $500 check.
38
Purpose: To recognize the best paper published in the IEEE
Transactions on Circuits and Systems. The award is based on
general quality, originality, contributions, subject matter and
timeliness. Anyone who is an author of a paper published in
the IEEE Transactions on Circuits and Systems during the two
calendar years preceding the award is eligible. Prize: Certificate and $250 check for each author (maximum of $1,000 per
award).
◊◊ Outstanding Young Author Award ◊◊
Purpose: To honor an especially meritorious paper published in any one of the CAS
Society's Transactions whose author at the date of submission is less than 30 years of
age. The award is based on general quality, originality, contributions, subject matter and
timeliness. Anyone who is an author of papers published in any one of the CAS Society
Transactions during the two calendar years preceding the award, who at the date of submission of the paper shall be less than 30 years of age is eligible. Prize: Certificate and
$250 check for each author (maximum of $1,000 per award).
Use these forms as a guide to electronically submit
nominations to Bing Sheu (see previous page).
DUE BY FEBRUARY 1, 2001
IEEE Circuits and Systems Society
2000 Outstanding Paper Award Nomination
Outstanding Young Author Award—CAD Transactions Best Paper Award
Guillemin-Cauer Award—CSVT Transactions Best Paper Award
Darlington Award—VLSI Transactions Best Paper Award
Paper Award Recommended:
_________________________________________________________________
Paper Title:
_____________________________________________________________________________
______________________________________________________________________________________
Paper Authors:
______________________________
______________________________
______________________________
______________________________
Paper Listing:
Name of Transactions:
_______________________________________________________
Month:
________________________ Year:
________________ Pages:
_________________
Nominator:
Name:
_________________________ Tel (day):
___________________ Tel (home-opt.): __________________
Address:
_______________________ Fax:
_______________________ E-mail: _________________________
______________________________
______________________________
Basis for Nomination:
Please give the reasons you believe this paper is deserving of the outstanding paper award. Judging is based upon general quality, originality,
contribution, subject matter, and timeliness. Continue on additional page(s).
IEEE Circuits and Systems Society
2000 Society/Achievement Award Nomination
Mac Van Valkenburg Award—Meritorious Service Award
Industrial Pioneer Award—Chapter-of-the-Year Award
Education Award—Technical Achievement Award
Name of Award: _____________________________Date: _________________________________________
Nominee:
Name:
_____________________________
Address:
_____________________________
Present Employment Position(s):
____________________
_____________________________
______________________________________________
_____________________________Highest Degree Attained:
__________________________
Telephone (day):
________________________________
Nominator:
Name:
Address:
_____________________________
_____________________________
_____________________________
_____________________________
Telephone (day):
________________________________
Tel (home-opt.):
__________________________________
Fax:
__________________________________________
E-mail:
________________________________________
1. Proposed Citation:
Provide a brief statement, not exceeding 50 words, giving the major accomplishments for which the award is being made. This will be used if the
nominee is selected as the awardee. Continue on separate page(s).
2. Basis for Nomination:
Prepare a statement not exceeding 750 words on why the candidate is being nominated for the award. This statement should then be followed by the
record of accomplishments of the candidate as an educator, and/or as a researcher, and/or as an administrator, and/or as an industrial pioneer, as
appropriate. Continue on separate page(s).
3. Short Biography (Not exceeding 2 pages):
Include degrees earned (list universities and granting dates); other postgraduate study; record of all positions held (chronologically starting with the
most recent position); IEEE activities and offices; other society memberships and offices; awards, honors, patents, inventions and other relevant
contributions. Continue on separate page(s).
4. Publications:
List all books, book chapters, and journal papers as well as 10 of the most important publications stating the engineering significance of each.
Continue on separate page(s).
5. References:
No more than five brief supporting letters from colleagues (and former students for the CAS Society Education Award) should be included with each
award nomination. List the names of the references on the nomination form. The reference letters can either be collected by the nominator and
forwarded unopened to Bing Sheu, or the references can be instructed to forward their recommendations directly to Dr. Sheu.
All reference letters must be received by the due date of the nominations, February 1, 2001. In the case of a re-nomination, references and other
materials can be re-used.
39
The Midwest Symposium on
Circuits and Systems: An Update
T
he 43rd meeting of the Midwest
Symposium on Circuits and Systems (MWSCAS) has just concluded,
and so it seems useful to recall some of
the history of this symposium, record the
events that took place at this meeting,
and list future venues.
Historical Overview
The MWSCAS is the oldest continuously operating conference devoted
to circuits and systems in the United
States [1] and possibly in the Americas.
It was started by Professors Myril B.
Reed and Ray M. Wainright in 1955, and
the first meeting was sponsored by the
University of Illinois at Urbana in cooperation with the Professional Group
on Circuit Theory of the Institute of
Radio Engineers (IRE). The second
meeting was held in 1956 at Michigan
State University, where the symposium
recently returned for its 43rd meeting.
Although the symposium was originally
designed as a regional conference, it has
gradually extended its area of venues so
that now it is a national or international
conference. It has been held in states
from Michigan to Texas and from California to New York, and it has been held
in Canada three times (Waterloo in
1973, Quebec in 1975, and Calgary in
1990), Mexico once (Puebla in 1983),
and Brazil once (Rio de Janeiro in
1995). A common quip at the meetings
is that the MWSCAS is always held in
the midwest of some city, county, state
or country.
The MWSCAS was an independent conference until 1989 when more
formal ties were established with the
Circuits and Systems Society and the
IEEE. While it was an independent
conference, its proceedings could be
obtained from Western Periodicals,
North Hollywood, California, except
for the proceedings of the meetings in
1987 and 1988 which can be obtained
from Elsevier Science Publishing
Company, New York. Proceedings of
40
meetings from 1989 to the present
time can be obtained from the IEEE.
In 1977, the first paper to receive
the Myril B. Reed Best Paper Award was
selected. The award was presented at the
meeting in 1978 to Prof. Ken Jenkins for
his paper “Techniques for High-Precision Digital Filtering with Multiple Processors” [2]. This award has become one
of the traditions of the MWSCAS and
is presented every year. Other traditions
and activities that have always been part
of the MWSCAS or which have been
added over the years are pre-conference
tutorial sessions, a conference reception,
a keynote address, plenary sessions,
Janie Fouke, dean of engineering at
Michigan State University and IEEE
Division 4 director, addressing the
audience at the Awards Banquet.
panel sessions, tours of local points of
interest, and, of course, a conference
banquet. More recently, the conference
has encouraged exhibitors, and although
the number has been small, interest in
the exhibits has been strong.
Since its inception, the MWSCAS
has been a student-friendly conference.
The presence of students at this conference is appreciated, and the MWSCAS
is always considering ideas to increase
student attendance. It is at this conference that graduate students often present
the results of their research for the first
time in a public forum. At the same time,
established researchers and other wellknown members of the engineering profession use this conference to communicate new results and ideas to their
peers. The presence of graduate students, established researchers, and other
well-known members of the engineering
profession makes for a good mix.
The 43rd Meeting
The most recent meeting of the
MWSCAS was held August 8–11 in
Lansing, Michigan, and was sponsored
by Michigan State University and the
Circuits and Systems Society. About 350
registrants were in attendance. Welcoming remarks were provided by M. Peter
McPherson, president of Michigan State
University, Janie Fouke, dean of engineering, and Fathi Salam, professor of
ECE and general chair. Professor Ken
Jenkins of Pennsylvania State University was the program chair, and Professor Hoda Abdel-Aty-Zohdy of Oakland
University was the program co-chair.
There were three plenary sessions this
year. The first was given by Professor
Mohsen Kavehard of Pennsylvania
State University and was entitled “Next
Generation Wireless Communications
System”. Professor Wasfy Michael of
the University of Central Florida presented the second plenary session, and
it had the intriguing title “Filtering and
Signal Processing: From Weight Reduction to Evolutionary Learning”. The
third plenary session, “Signal Processing by Floccular and Ventral Cells”, was
presented by Dr. Stephen Highstein of
the Washington University School of
Medicine. Generally, the plenary sessions at the MWSCAS are focussed on
new topics that are related in some way
to network theory or to the design of
new circuits or to other fields of science
that may contribute to these areas in the
future; and this year’s plenary sessions
were no exception.
Two informative panel sessions
were included in this year’s meeting.
In the first, moderated by Professor
Robert W. Newcomb of the University of Maryland, the discussion centered on “Internet Based Design and
Test”. Professor Rui de Figueiredo of
the University of California, Irvine,
and past president of the Circuits and
Systems Society, moderated the second panel session on “The Role of
Circuits and Systems Technologies in
Emerging Telecommunications Scenarios”. The topics of both panel sessions are important to engineers in the
circuits and systems community and
were exciting to most of the attendees.
Over the years, the scope of the
MWSCAS has broadened, although
there were papers presented even in
the first meeting discussing digital circuits and digital circuit design philosophies. The 43rd meeting included
technical tracks in analog circuits and
signal processing, general circuits and
systems, neural networks and systems, computer-aided design, digital
signal processing, VLSI circuits and
systems, multi-media and communication, and sensors, MEMS and industrial applications. These tracks
contained a total of 50 sessions with
each session consisting of at least six
or seven papers. There were sessions
entitled Recent Advances in Communication Systems, Robotics and Control, Bio-Inspired Signals and Systems, and Topics on Fuzzy Logic in
addition to sessions such as Topics on
Analog Circuits, Solid State Circuits
and Devices, and Current Issues in
CMOS Circuit Design.
A unique event at this year’s symposium was a luncheon to honor Professor Robert Newcomb and his wife
Sally. Dr. de Figueiredo announced
that Dr. Newcomb was being honored
for the beneficial impact his work has
had on the MWSCAS, on the Circuits
and Systems Society, and on electrical engineering at the national and international levels. He emphasized that
Dr. Newcomb was one of the inventors of microelectronics, a pioneer in
neural systems, and a pioneer in models for biological systems. Dr. Fathi
Salam stated that Dr. Newcomb puts
a human face on all his technical ac-
tivities, and he treats everyone with
warmth and depth. Dr. Ken Jenkins
remarked that Dr. Newcomb is known
for working with and helping students, accompanying them to conferences and introducing them to other
people in their fields. Dr. M. N. S.
Swamy mentioned that he has known
Dr. Newcomb for 35 years not only
for his contributions to circuit theory
but also as a wonderful human being
and recalled that Dr. Newcomb is also
a poet and has a long-term interest in
poetry and literature. Dr. Majid
Ahmadi then presented Dr. Newcomb
with an album containing notes and
signatures from well-wishers who
were present at the luncheon. Dr. Igor
Filanovsky asserted that Dr.
Newcomb’s many papers and books
were always clear and even withstood
Russian translations. He recalled an
early paper in active synthesis by
Robert W. Newcomb, honored for the
beneficial impact his work has had on the
MWSCAS, on the Circuits and Systems
Society, and on electrical engineering.
Kerwin, Huelsman, and Newcomb
[3–4] in which the KHN circuit was
introduced and stated, “When your
work is reduced to one letter, you
have become a classic researcher.” He
conveyed the thanks of thousands of
Russian radio engineers to Dr.
Newcomb. Dr. Mona Zaghloul
thanked Dr. Newcomb on behalf of all
the students he has mentored and for
being such a good mentor for her. Dr.
Newcomb was then prevailed upon to
say a few words. He commented that
he had roots in Michigan from his
grandfather on his mother’s side. He
ended the proceedings by stating that
he has taken great pride and joy in
working with students and seeing
them progress in life.
The banquet at the MWSCAS is
usually an occasion for attendees to
hear an important address. This year,
Dr. de Figueiredo introduced the main
banquet speaker, Dean Janie Foulke,
who spoke more in her capacity as director of Division 10 (Systems and
Controls) of the IEEE rather than as
dean of engineering at Michigan State
University. Dr. Foulke based her remarks on the book she edited entitled
Engineering Tomorrow [5] in which
50 engineers and scientists share their
thoughts about engineering in the future. She conveyed a brief synopsis of
some of the ideas in this book to the
audience and emphasized that she is
optimistic about the future.
The conference banquet is also
utilized to announce the winners of
the best paper award and other prizes.
This year the Myril B. Reed Best Paper Award was given to Samuel L.
SanGregory, Charles Brothers, and
David Gallagher of the Air Force Institute of Technology, WrightPatterson Air Force Base and to
Raymond Siferd of Wright State University for their paper “A Fast, LowPower Logarithm Approximation
with CMOS VLSI Implementation”
which was presented at the MWSCAS
held in Las Cruces in 1999 [6].
In recent years, a student paper
contest has been held as one means to
encourage student participation, and
the names of the winners are announced at the banquet. This year
there were about forty entries in this
contest, split almost evenly between
papers that addressed analog topics
and those that were devoted to digital topics. Since the total number of
papers submitted was quite an increase from the previous year, the
contest was split into two contests
corresponding to the natural split in
the topics addressed by the papers.
Each contest had a separate group of
judges and a separate set of prizes.
Prizes consisted of checks for $300
for first place, $200 for second place,
and $100 for third place for each con. . . continued on Page 42
41
MWSCAS Report … continued from Page 41
test. Tables I and II list the winners for
each contest.
Table I
Winning Student Papers in Analog
Contest at 43rd Meeting
First Place:
“CMOS 5-10 GHz Oscillators for Low
Voltage RF Applications” by Ahmed H.
Mostafa, Mourad N. El-Gamal and
Ramez A. Rafla, McGill University.
Second Place:
“A New Charge Redistribution D/A and
A/D Converter Technique - Pseudo C2C Ladder” by Lin Cong and William
C. Black, Iowa State University.
Third Place (tie):
students who participated in the contests
as well as their faculty advisors are to
be congratulated for making these paper
competitions lively and strong.
Future Venues
The 44th MWSCAS is scheduled
for August 13–17, 2001, in Dayton,
Ohio. Dr. Robert L. Ewing (robert.
ewing@wpafb.af.mil) is the general
chair. Professor Harold Carter is cochair, and Gary B. Lamont chairs the
Technical Program Committee with
aid from Professors Belle Shenoi,
Hoda Abdel-Aty-Zohdy, and Mohammed Ismail. The conference is being
sponsored by the College of Engineering at Wright State University, the
Dayton IEEE Section, and the IEEE
“Charge-Mode Parallel Architecture for
Matrix-Vector Multiplication” by Roman Genov and Gert Cauwenberghs,
Johns Hopkins University.
“A Novel Linear Tunable MOS
Transconductor” by Ko-Chi Kuo and
Adrian Leuciuc, SUNY at Stony Brook.
Table II
cal program chair is Dr. Keith Teague
(teague@okstate.edu). Dr. Soderstrand is one of the “old hands” of the
MWSCAS, having chaired the very
successful 40th meeting at Sacramento, California.
Conclusions
The MWSCAS is probably one of
the better kept secrets of the circuits
and systems community. However, it
has continued to serve the purpose of
disseminating research results, not
only in the circuits and systems areas,
but also in a wide variety of other areas, for almost half a century. So in
addition to the attendees ranging from
graduate students to well-established
researchers, the range of technical interests of the attendees is quite broad.
It is a good conference to attend to see
what is happening in your field, to find
out what is happening in other fields
that may affect your field, to introduce
students to people they ought to know
in their technical areas, and to enjoy
the camaraderie that this conference
seems to foster.
References
Winning Student Papers in Digital
Contest at 43rd Meeting
[1]
First Place:
“Quality of Data Reconstruction Using
Stochastic Encoding and an Integrating
Receiver” by Alyssa Apsel and Andreas
Andreou, Johns Hopkins University.
Second Place:
“Efficient Polyphase Decomposition of
Comb Decimation Filters in SigmaDelta Analog-to-Digital Converters” by
H. Aboushady, Y. Dumonteix, M. M.
Louerat, and H. Mehrez, University of
Paris.
Third Place (tie):
“A VLSI Architecture for Soft-Output
PR4 Detection” by Warren J. Gross,
Vincent C. Gaudet, and P. Glenn Gulak,
University of Toronto.
“A Digital Frequency Synthesizer for a
2.4 GHz Fast Frequency Hopping
Transceiver” by Riku Uusikartano and
Jarkko Niittylahti, Tampere University
of Technology.
In both contests, there was a tie for
third place. These students and all the
42
[2]
Professor Fathi Salam, general chair of
MWSCAS 2000, welcoming the Symposium
audience.
Circuits and Systems Society. Support
for this meeting is provided by the
University of Cincinnati, Ohio State
University, and the Air Force Institute
of Technology. Proposed papers for
this conference can be submitted electronically to the web site (see
www.mwscas.org) or five hard copies
can be sent to Dr. Mohammed Ismail,
Ohio State University, 205 Dreese
Laboratory, 2015 Neil Avenue, Columbus, OH 43210–1272.
In 2002, the 45th MWSCAS is
scheduled to be held in Tulsa, Oklahoma under the auspices of Oklahoma
State University. The general chair is
Dr. Michael A. Soderstrand (sodersm
@okstate.edu), chairman of the ECE
Department at OSU; and the techni-
[3]
[4]
[5]
[6]
Peter B. Aronhime and Donald J. Scheer,
“The MWSCAS: A 42-Year History”,
IEEE Circuits and Devices Magazine,
vol. 13, no. 4, pp. 42–48, July 1997.
W. K. Jenkins, “Techniques for High-Precision Digital Filtering with Multiple
Microprocessors”, Proceedings of the
MWSCAS, Lubbock, Texas, pp. 58–62,
August 15–17, 1977.
W. J. Kerwin, L. P. Huelsman, and R. W.
Newcomb, “State-Variable Synthesis for
Insensitive Integrated Circuit Transfer
Functions”, IEEE Journal of Solid-State
Circuits, vol. SC–2, pp. 87–92, September 1967.
L. P. Huelsman and P. E. Allen, Introduction to the Theory and Design of Active
Filters. New York: McGraw-Hill, pp.
214–232, 1980.
Janie Fouke, ed., Engineering Tomorrow:
Today’s Technology Experts Envision the
Next Century. Piscataway, NJ: IEEE
Press, 2000.
Samuel L. SanGregory, Charles Brothers,
David Gallagher, and Raymond Siferd,
“A Fast, Low-Power Logarithm Approximation with CMOS VLSI Implementation”, IEEE Proceedings of the MWSCAS,
vol. 1, Las Cruces, New Mexico, pp.
388–391, August 8–11, 1999.
Peter Aronhime
ECE Dept.
University of Louisville
The CNN Young Researcher
Contest 2000
by Bertram Shi, Csaba Rekeczky, Marco Gilli and Mamoru Tanaka
T
he CAS Society Technical Committee on Cellular Neural Networks and
Array Computing recently initiated a
CNN Young Researcher Contest. The organizing committee consisted of Csaba
Rekeczky, Bert Shi, Marco Gilli and
Mamoru Tanaka. It was held in conjunction with the 6th IEEE International Workshop on Cellular Neural Networks and
Their Applications (CNNA 2000), which
was held in Catania, Italy between 23–25
May 2000. The goal was to provide students and young researchers worldwide
with an opportunity to familiarize themselves with the capabilities of the CNN
Universal Machine and to hone their
analogic programming skills by competing against others. Cash prizes of US$500,
US$300, US$200 and certificates were
awarded to the top three entries. Student
winners were also given fee offsets to assist them in attending CNNA 2000 to
present their results.
Participants in the contest were given
the task of deriving an algorithm to segment and classify watermarks embedded
into a set of images. The algorithm was required to be executable on a Cellular Neu-
ral Network Universal Machine. There
were three classes of watermarks (sharks,
turtles and eagles). Each class contained
12 binary images: 3 different sizes of a
prototype image in 4 different orientations
(rotated by 90 degrees). The watermarks
were embedded into 21 training images of
natural seashore via an undisclosed sequence of nonlinear operations. To ensure
that all entries would be treated fairly,
carefully defined numerical evaluations
were released to all participants in advance. Although the criteria were known
in advance, they were computed based on
test images which were similar, but not
identical to those in the training set and
which were not released to the participants. The entries were evaluated in terms
of their quality of the watermark segmentation and classification, their computational (time) complexity and their hardware complexity. These three individual
scores were then combined into a global
figure of merit, which was used to determine the winning entries. Figure 1 shows
example input/output images from the
segmentation algorithm of one of the contest entries.
. . . continued on Page 44
(input.tif)
(output.tif)
(reference.tif)
(a)
(b)
(c)
Figure 1. (a) Sample input image, (b) output image of the segmentation from one of the contest entries, (c) the reference image
used to generate the watermarked input image and to evaluate the segmentation quality of the output image.
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CNNA Contest … continued from Page 43
A web page (located at http://
lab.analogic.sztaki.hu/cnna2000) was set
up which contained the description of the
contest and a description of the quantitative evaluation criteria used to decide the
winning entries. After registering through
the web page, participants were able to
download a student version of a commercially available analogic CNN algorithm
THE ADVENTURES OF …
…THE 'UMBLE OHM
…Shlomo Karni
AMPHi(t)HEATER
simulator and programming environment,
the watermark images and the training
images. Participants were also able to
track the performance of their submitted
algorithms on testing images through this
web page.
Judging by the response, the contest
achieved its goal. Before the contest deadline, the web page registered over 900 hits
from over 250 unique IP addresses. In total, 23 users registered for the contest from
a variety of countries in North America,
Europe and Asia. Authors of the top three
winning entries were invited to present
their results at the 6th IEEE International
Workshop on Cellular Neural Networks
and Their Applications (CNNA 2000) held
44
in Catania, Italy on 24 May 2000. The top
three winning entries were
1. Péter Földesy (Focal Plane Array Processors Research Group, IMSE-CNM,
Seville, Spain)
2. Dávid Bálya (Vision Research Laboratory, MCB-UCB, Berkeley, USA)
3. David Monnin (French-German Research Institute of Saint-Louis, SaintLouis, France)
Based upon the success of this contest, the IEEE CAS Technical Activities
Board has agreed to sponsor a biannual
CNN Young Researcher Contest. The contest will be held in conjunction with every IEEE International Workshop on Cellular Neural Networks and Their Applications. The next contest will be held in 2002
and the results will be announced in
Frankfurt, Germany. Keep your eyes
posted for announcements, which
should be coming out in 2001. Readers
who cannot wait that long are encouraged to point their browsers to http://
lab.analogic.sztaki.hu/cnna2000, which
still contains all necessary information, so
that they can try the contest task for themselves and see how they would have done.
CHUA RECEIVES
NEURAL NETWORKS
PIONEER AWARD
P
rofessor Leon Chua is the recipient of the year 2000 Neural Networks Pioneer Award. The award was
presented at the International Joint
Conference on Neural Networks
(IJCNN 2000), held in Como, Italy, on
July 24–27. The Neural Networks Pioneer Award is the most prestigious
award given annually by the IEEE
Neural Networks Council. Previous
winners include Teuvo Kohonen,
Stephen Grossberg, Bernard Widrow,
Shun-Ichi Amari, Paul Webos,
Michael Arbib, John Hopfield, and
Geoffrey Hinton. The award consists
of a plaque and $2,000 travelling expenses for the winner and spouse.
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2000 IEEE Asia-Pacific Conference
on Circuits and Systems
Electronic Communication Systems
December 4–7, 2000
Crystal Palace Hotel, Tianjin, China
December 17–20, 2000
http://www.icecs2k.polymtl.ca
Technical Program Co-Chair
Professor Yoji Kajitani
Tokyo Institute of Technology, Japan
Professor Runtao Ding
Tianjin University, Tianjin, China
Tutorials
Dr. Ibrahim Hajj
University of Illinois, USA
E-mail: i-hajj@uiuc.edu
Special Sessions
Dr. Fadi Kurdahi
University of California, Irvine, USA
E-mail: kurdahi@ece.uci.edu
Requests for information:
ICECS’2K Secreteriat
School of Engineering and Architecture
The Lebanese American University
P.O. Box 36, Byblos, Lebanon
FAX: 961 9 944 851
E-mail: genasr@lau.edu.lb
sawan@vlsi.polymtl.ca
Le
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Web site:
http://www.eee.hku.hk/misc/ieeecas/
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Visit our web site at http://www.iccad.com
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Program Vice Chair
Lawrence T. Pileggi
CMU
pileggi@ece.cmu.edu
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Program Chair
Rolf Ernst
Tech. Univ. of Braunschweig
ernst@ida.ing.tu-bs.de
For further information, please contact:
Professor Tony T. S. Ng
Department of Electrical &
Electronic Engineering
The University of Hong Kong
Pokfulam Road, Hong Kong
Tel: +852-28592710
Fax: +852-25598738
E-mail: tsng@eee.hku.hk
Places
Conference Manager
Kevin Lepine
MP Associates, Inc.
5305 Spine Rd., Ste. A
Boulder, CO 80301
303-530-4562
303-530-4334
kevin@dac.com
Organization Committee
Tony T. S. Ng (Chairman)
Qiuting Huang
George Moschytz (Co-Chairman) Markus Halfenstein
Ruey-Wen Liu
Magdy Bayoumi
Hari Reddy
Chris Toumazou
Yrjo Neuvo
Geert De Veirman
Places
General Chair
Ellen Sentovich
Cadence Berkeley Labs
2001 Addison St. 3rd Floor
Berkeley, CA 94704-1103
510-647-2807
510-486-0205
ellens@cadence.com
This three-day workshop addresses implementation and application
issues for 3rd Generation Mobile Communication. The program will
combine presentations by experts in the field from industry and
academia, with panel and informal discussions.
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Hong Kong Convention & Exhibition Center
HONG KONG
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DoubleTree Hotel
San José, California
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November 29–December 1, 2000
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ICCAD–2000
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4th IEEE CAS Workshop on Emerging
Technologies in Circuits and Systems
Third Generation Mobile
Technologies and Applications
The rapid progress in process technology development combined with the expanding diversity of information processing applications is placing enormous
demands on CAD tool development. The International Conference on Computer Aided Design 2000 (ICCAD) offers a place for CAD developers and VLSI
designers to meet and exchange ideas about the problems and solutions in
the era of system-on-a-chip.
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APCCAS2000 Conference Secretariat
School of Electronic Information Engineering
Tianjin University, Tianjin 300072, China
Fax : 86-22- 2740-1471
Tel : 86-22- 2740-5623
E-mail : hywang@tju.edu.cn
n
General Co-Chair
Professor Zhenming Chai
Institute of Electronics
Academia Sinica
Beijing, China
Technical Program Chair
Dr. Mohamad Sawan
Ecole Polytechnique de Montreal
Email: sawan@vlsi.polymtl.ca
no
Technical Program Chair
Professor Yih-Fang Huang
University of Notre Dame U.S.A.
General Chair
Dr. Abdallah Sfeir
Lebanese American Univ., Lebanon
Email: asfeir@lau.edu.lb
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General Chair
Professor Yongshi Wu
Tianjin University, Tianjin, China
The IEEE International Conference on Electronics, Circuits and Systems (ICECS)
will celebrate the year 2000 in Beirut. For the first time an IEEE International Conference on Electronics, Circuits and Systems will be held in Lebanon. The venue
will be in the continuously expanded and modern region of Lebanon located at the
north of Beirut—the heart of a lively multicultural and Mediterranean country.
ba
The 2000 IEEE Asia-Pacific Conference on Circuits and Systems
(APCCAS2000) is the fifth in the series of biennial Asia-Pacific Conferences
sponsored by the IEEE Circuits and Systems Society, Chinese Institute of Electronics (CIE), IEEE Beijing Section, IEEE CAS Beijing Chapter and Tianjin
University of China. It will be held at the Crystal Palace Hotel, Tianjin, China
on December 4–7, 2000. The conference will be devoted to all aspects of theory,
design, modeling, simulation, and applications of circuits and systems. Plenary sessions, special sessions, invited talks, and tutorials on specific advanced
topics will also be included in the program.
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Kaslik, LEBANON
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APCCAS2000
http://www.tju.edu.cn/news/apccas2000
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November 13–17, 2000
Registration Information
AMSC, Texas A&M University
ATTN: Ella Gallagher
Dept. of Electrical Engineering
College Station, TX 77843-3128 USA
Tel: (979) 845–9587
Fax: (979) 845–7161
E-mail: ella@ee.tamu.edu
October 16, 2000
December 4, 2000
January 8, 2001
D
al
la
s
Registration deadline is October 24
Internet Information
http://amsc.tamu.edu/shortcourses
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2001 SOUTHWEST
SYMPOSIUM ON
MIXED-SIGNAL DESIGN
8th IEEE International Conference on Electronics, Circuits and Systems
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February 25–27, 2001
Austin, Texas, U.S.A.
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us
Other information:
http://www.tuiasi.ro/events/scs2001
http://www-imt.unine.ch/scs2001
lgoras@etc.tuiasi.ro ( Prof. Liviu Goras )
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Secretariat:
Phone: +40 32 142283
FAX: +40 32 217720 or +40 32 278628
The fifth edition of the International Symposium on Signals, Circuits and Systems will be held in Iasi at the Faculty of Electronics and Telecommunications, Technical University “Gh. Asachi”.
Iasi, the oldest academic center of Romania, is located in the
North-Eastern part of the country and can be reached from
Bucharest by plane or by train. A wine tasting and a one day post
symposium trip in the neighboring region, well known for its
wonderful monasteries, will be organized.
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Address for correspondence:
SCS’2001 International Symposium
Faculty of Electronics & Telecommunications
“Gh. Asachi” Technical University of Iasi
Bd. Carol 11, Iasi, 6600, ROMANIA
Iasi, Romania
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A
July 10–11, 2001
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The Fifth International Symposium
on Signals, Circuits and Systems
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Technical Program Chair
Prof. Franco Maloberti
Department of Electrical Engineering
Texas A&M University
College Station
Texas 77843
USA
Email: franco@ele.unipv.it
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Further Information
For details on the electronic submission
procedure, please go to
http://www.ece.arizona.edu
conferences/ssmsd
ICECS 2001 Secretariat
Department of Microelectronics
Faculty of Engineering
University of Malta
Msida MSD 06
Malta
Europe
E-mail: icecs01@eng.um.edu.mt
Tel: (+356) 346760
Fax: (+356) 343577
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Author’s Schedule
Submission of three-page summary:
October 13, 2000
Notification of acceptance:
December 15, 2000
Final camera-ready paper & registration due:
January 15, 2001
General Chair
Dr. Joseph Micallef
Department of Microelectronics
University of Malta
Msida MSD06
Malta
Europe
Email: jjmica@eng.um.edu.mt
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Overview
The 2001 Southwest Symposium on Mixed-Signal
Design is sponsored by the University of Arizona
Dept. of ECE in cooperation with the IEEE SolidState Circuits Society. The symposium will bring
together researchers in academia, industry, and government from the areas of CAD tools and mixedsignal circuit design. This will allow not only the
presentation of the latest developments in each field,
but also interaction between the areas in order to
expedite the development of improved integrated
systems and “systems on a chip”. Of particular interest is the integration of mixed-signal types, such
as analog, digital, RF, optical, and microwave circuits and systems.
Schedule for Authors:
Proposals for special sessions, plenary sessions, and short courses: October 15, 2000
Deadline for submission of draft papers: February 15, 2001
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General Chair
General Co-Chair
John Choma, Jr.
Jo Dale Carothers
Univ. of Southern Univ. of Arizona
California
Program Chair
Franco Maloberti
Texas A&M Univ.
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September2–5, 2001 The Westin Dragonara Resort, Malta
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http://www.eng.um.edu.mt/microelectronics/icecs2001
ICECS 2001, the 8th IEEE International Conference on Electronics, Circuits and Systems is a major international conference which includes regular, special and poster sessions on topics covering analogue circuits and signal processing, general
circuits and systems, digital signal processing, VLSI, multimedia and communication, computational methods and optimization, neural systems, control systems, industrial and biomedical applications, and electronic education.
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ICECS’01 ICECS’01 ICECS’01
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< < CALL FOR PAPERS > >
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* * First Call for Papers * *
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http://ewh.ieee.org/soc/cas/dallas/wks2
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For further information visit:
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Author’s Schedule:
Deadline for submission of papers
Notification of paper acceptance
Deadline for camera-ready paper
as
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Analog and
Mixed-Signal Testing
Short Course
Who Should Attend
This course is intended for new and experienced electric and electronic engineers who need intensive concentrated information on the state-of-the-art of Analog
and Mixed-Signal Circuits Testing. In particular this
course is intended for: • IC testing engineers • Analog
and Digital Circuit Designers • Application engineers.
The IEEE 2nd Dallas CAS Workshop on Low Voltage and Low Power Mixed-Signal Circuits & Systems is being
conducted under the aegis of the IEEE Dallas Section, Circuits & Systems Society. The workshop will include invited lectures and poster sessions. Leading experts Dr. John Choma, Dr. Randall Geiger, Dr. Franco Maloberti, and
Dr. Jaime Ramírez-Angulo will present the latest techniques and challenges involved in low power RF design, low voltage analog circuits, low voltage sigma-delta and nyquist rate data converters. Prospective authors are invited to submit
a one-page summary of their posters reporting original work in the area of low voltage/low power mixed-signal design.
Registration Chair:
Dr. Oscar Moreira-Tamayo
omoreira@ti.com
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TEXAS A&M UNIVERSITY
Department of Electrical Engineering
Monday, 26th March 2001
Dallas, Texas
Technical Chair:
Dr. Joseph Varrientos
joseph.varrientos@dalsemi.com
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Analog and Mixed Signal Center
2000
IEEE 2nd Dallas CAS Workshop on
Low Voltage Mixed Signal
Circuits and Systems
General Chair:
Dr. Gabriele Manganaro
gabriele.manganaro@ieee.org
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ANNOUNCEMENT AND CALL FOR PAPERS
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Wireless Networks … continued from Page 24
[5] 3GPP, Radio Interface Architecture, 3GPP TS 25.301, version 3.1.0, July 1999.
[6] E. Dahlman, P. Beming, J. Knutsson, F. Ovestjo, M.
Persson, and C. Roobol, “WCDMA- The Radio Interface
for Future Mobile Multimedia Communications”, IEEE
Transactions on Vehicular Technology, vol. 47, no. 4, 1998.
[7] Michael Meyer, “TCP Performance over GPRS”, Proceedings of the Wireless Communications and Networking Conference, pp. 1248–1252, 1999.
[8] M. Allman, et al., “Ongoing TCP Research Related to Satellites”, Internet-Draft: http://www.ietf.org/internet drafts/
draft-ietf-tcpsat-res-issues-11.txt, September 28, 1999.
[9] S. Dawkins, et al., “End-to-End Performance Implications
of Links with Errors”, Internet-Draft: http://www.ietf.org/
internet-drafts/draft ietf-pilc-error-02.txt, October 26,
1999.
[10] S. Dawkins, et al., “End-to-End Performance Implications
of Slow Links”, Internet-Draft: http://www.ietf.org/
internet-drafts/draft-ietf-pilc-slow-02.txt, October 21,
1999.
[11] S. Gruhl, A. Echihabi, T. Rachidi, M. Link, and M. Söllner,
“A Demonstrator for Real-Time Multimedia Sessions over
3rd Generation Wireless Networks”, to be published in Proceedings of ICME 2000, IEEE Press.
[12] “Packet-Based Multimedia Communications Systems”, International Telecommunications Union, Geneva, Switzerland, ITU-T Recommendation H. 323, 1998.
[13] “Call Signaling Protocols and Media Stream Packetization
for Packet-Based Multimedia Communication Systems,”
International Telecommunications Union, Geneva, Switzerland, ITU-T Recommendation H. 225.0, 1998.
[14] “Control of Communications between Visual Telephone
Systems and Terminal Equipment,” International Telecommunications Union, Geneva, Switzerland, ITU-T Recommendation H.245, 1998.
[15] H. Schulzrinne, et al., “RTP: a Transport Protocol for RealTime Applications,” Request for Comments (Proposed
Standard) RFC 1889, Internet Engineering Task Force,
January 1996.
[16] L. Zang, et al., “RSVP: A New Resource Reservation Protocol,” IEEE Network, pp. 8–18, September 1993.
[17] H. Schulzrinne, A. Rao, and R. Lanphier, “Real-Time
Streaming Protocol (RTSP)”, Internet Draft, Internet Engineering Task Force, March 1997.
IEEE CAS Newsletter
The Circuits and Systems Society’s homepage web site is:
http:// www.ieee-cas.org
Society Officers
B.J. Sheu, President
H.C. Reddy, President-Elect
M.E. Zaghloul, Vice President, Technical Activities
G.A. De Veirman, Vice President, Conferences
G. De Micheli, Vice President, Publications
A. Dunlop, Vice President, Regions 1–7
A. Davies, Vice President, Region 8
J. E. Cousseau, Vice President, Region 9
T.S. Ng, Vice President, Region 10
I.N. Hajj, Vice President, Administration
G. Moschytz, Past President
Board of Governors
W. Black
R.J. Marks, II
J.A. Nossek
W. Wolf
E. Yoffa
E. Friedman
N. Fujii
I. Galton
M. Green
C. Toumazou
G.E. Gielen
R. Gupta
M. Hasler
P. Pirsch
H. Yasuura
Representatives
E. Friedman, Solid-State
Circuits Society
C.Y. Wu, J. Zurada, IEEE
Neural Networks Council
M.E. Zaghloul, Sensors
Council
Standing Committees
G. Moschytz, Awards
L.O. Chua, Fellows
R.J.P. de Figueiredo,
Nominations
K. Thulasiraman, Constitution/Bylaws
Transformers with High Power Density and High
Efficiency”, IEE Electronics Letters, vol. 36, no. 11, May
2000, pp. 943–944.
[16] S. Y. R. Hui, S. C. Tang, and H. S. H. Chung, “Some Electromagnetic Aspects of Coreless PCB Transformers”,
IEEE Transactions on Power Electronics, vol. 15, no. 4,
July 2000.
[17] S. Y. R. Hui and S. C. Tang, “Coreless Printed Circuit
Board Transformers”, US patent pending
[18] Analog Devices Manual: Isolation Amplifier AD215.
Editors
M.K. Sain, IEEE CAS
Newsletter
M.N.S. Swamy, IEEE CAS I
Transactions
C. Toumazou, IEEE CAS II
Transactions
G. De Micheli, IEEE CAD
Transactions
W. Li, IEEE Transactions on
Video Technology
M.T. Sun, Multimedia
Transactions
W. Wolf, IEEE Transactions
on VLSI Systems
M.E. Zaghloul, Circuits &
Devices Magazine
Corresponding Editor
A.J. Payne, IEEE CAS II
Transactions
Dist. Lecturer Program
Conference Chairs
E. Yoffa
D. Skellern, G. Hellestrand,
2001 ISCAS Co-Chairman
E.M. Sentovich, 2000 ICCAD
General Chairman
C. Chase, 2000 ICCD
General Chairman
J. Rabaey, 2001 DAC
General Chairman
Y.-S. Wu, 2000 APCCAS
General Chairman
F.M. Salam, 2000 MWSCAS
General Chairman
A. Sfeir, 2000 ICECS
General Chairman
Technical Committees
Coreless PCB Transformers … continued from Page 15
G. Ron Chen, Nonlinear
Circuits and Systems
A. Ioinovici, Power Systems
& Power Electronics Circuits
G. Barrows, Sensors &
Micromachining
J. Ostermann, Visual Signal
Processing
R. Sridhar, VLSI Systems and
Applications
G. Cauwenberghs, Analog
Signal Processing
T. Roska, Cellular Neural
Networks & Array Computing
M.A. Bayoumi, CAS for
Communications
R. Gupta, Computer-Aided
Network Design
P. Diniz, Digital Signal
Processing
C.S. Li, Multimedia Systems
and Applications
M. Ahmadi, Neural Systems
and Applications
Administrator
B.Wehner
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2001 IEEE International Symposium on Circuits and Systems
May 6–9, 2001
Sydney Convention and Exhibition Center
Darling Harbor, Sydney, Australia
SYSTEMS of CIRCUITS and MIXED TECHNOLOGY ELEMENTS
The 2001 IEEE International Symposium on Circuits and Systems will
be held in Sydney, Australia. The Symposium is sponsored by the IEEE Circuits and Systems Society.
The Symposium will include: regular sessions; plenary sessions on advanced aspects of theory, design and applications of circuits and systems; and
short courses/tutorials linked with special sessions on wireless, mixed technology systems engineering, high speed devices and modelling, signal and
video processing, and low power high speed VLSI design.
Web Site: http://www.elec.mq.edu.au/iscas01/
CONFERENCE CO-CHAIRMEN:
Professor David Skellern
Electronics Department (E6A 247)
Division of Information and Communication Sciences
Macquarie University
NSW 2109 Australia
daves@elec.mq.edu.au
Tel: +61 2 9850 9145; Fax No: +61 2 9850 918
http://www.elec.mq.edu.au/
Professor Graham Hellestrand
Address: VaST Systems Technology Corporation
1230 Oakmead Parkway
Suite 314, Sunnyvale, CA 94806 USA
Tel: +1 408 328 0909 Fax No: +1 408 328 0945
g.hellestrand@vastsystems.com
http://www.vastsystems.com
THE INSTITUTE OF ELECTRICAL
& ELECTRONICS ENGINEERS, INC.
445 HOES LANE
PISCATAWAY, NJ 08855
48