EMC Society of Australia
NEWSLETTER
www.emcsa.org.au
A Joint Publication of the EMC Society of Australia (Engineers Aust.)
and the Victorian (Aust.) Chapter of IEEE EMC Society
Issue Number 56
March 2012
Engineers Australia
11 National Circuit Barton ACT 2600
EMC Society of Australia Newsletter
1
EMC SOCIETY COUNCIL
The EMC Society is a technical and learned society within Engineers Australia,
established to promote the science and practice of Electromagnetic Compatibility through Australia and the region.
NATIONAL COUNCIL
STATE REPRESENTATIVES
Chairman
Secretary
Treasurer
Member
Member
Member
Member
Member
Member
Member
Member
South Australia, Paul Kay, paul.kay1@defence.gov.au
Queensland, Matthew Chorley, matthew.b.chorley@boeing.com
WA, Franz Schlagenhaufer, F.Schlagenhaufer@curtin.edu.au
Mark Mifsud
Andrew Walters
Kingsley McRae
Paul Kay
Franz Schlagenhaufer
Gordana Klaric Felic
Jean-Michel Redouté
Graeme Madigan
Chris Zombolas
Arthur Weedon
Phu Nguyen
PORTFOLIOS
Newsletter Editor
Webmaster
Media
Membership
Publicity
IEEE Liaison
Gordana Klaric Felic
Paul Kay
Mark Mifsud
Franz Schlagenhaufer,
Andrew Walters
Jean-Michel Redouté,
gordana.felic@nicta.com.au
paul.kay1@defence.gov.au
emcmifsud@hotmail.com
F.Schlagenhaufer@curtin.edu.au
Andrew.Walters@dsto.defence.gov.au
jean-michel.redoute@monash.edu
ichel.redoute@monash.edu
Letter from the Editor,
Welcome to the first Newsletter of this year. As you can see above some new
members have joined the EMCSA Council and some of them have already made
a contribution to this issue of the newsletter. The IEEE EMC Society chairman,
Jean-Michel Redoute wrote an article on the EMC effects in integrated circuits,
a topic of his research.
This time I’ve also included a paper form the EMCSA Symposium 2004
presented and written by Andrew Walters. The paper deals with investigation
into field and surface current intensification for whole aircraft testing in a TEM
cell.
In this issue you will find the answer to the test question set by Mark Montrose
in the previous issue.
The EMC Society presentations have commenced again this year. The first presentation in February delivered
by Dr Bruce Archambeault was a great and highly valued event. I have added some pictures and information
about his presentation.
Also, this year I have introduced a column on the Society News for all members to inform or post anything
about their activities that might interest our EMC community.
If you would like to publish an article on the EMC and electromagnetic topics you are more than welcome.
Please use this Newsletter as an opportunity for you to contribute to the Society, promote your work or research
and share your experience with EMC colleagues. Manuscripts can be sent at gordana.felic@nicta.com.au
gordana.felic@nicta.com.au.
Gordana Klaric Felic
2 EMC Society of Australia Newsletter
Message from the Chairman,
2012 promises to be landmark year for the EMC Society of Australia. We have
elected a new council and there are many new faces on the council.
Three long serving members on the council members have hung up their boots
and I would like to acknowledge their contributions.
John Hyne was my predecessor as chairman for over 9 years and was one of the
founding members on the council. Malcolm Mulcare was also a founding
member on the council and also acted as the liaison with the IEEE. Paul Payne
has been on the council for over 9 years and has been very active in assisting in
the various activities organized by the society and also the member coordinator.
On behalf of all EMCSA members I wish to thank you for all contributions over
the years and wish all the best with your future endeavours.
Despite losing 3 council members the council has increased to 11 members as
the following additional members were ratified at a meeting on the 8th of February 2012. They are Jean Michel
Redoute, Graeme Madigan, Arthur Weedon, Chris Zombolas and Phu Nguyen.
Our interstate contingent has increased which is in line with our aim to make the council more representative of
our membership.
I was voted chairman, Andrew Walters was elected Secretary and Kingsley McRae was elected Treasurer.
Gordana Felic volunteered to be the newsletter editor again after performing this task admirably last year. Paul
Kay is taking over the role of Webmaster from John Hyne and is also the Chapter Chair for South Australia.
Franz Schlagenhaufer is the new membership coordinator as well as being the Chapter Chair for Western
Australia. Jean Michel Redoute will be the IEEE liaison.
As some of you may already know Australia has been offered the Asia Pacific EMC Symposium in 2013.
Engineers Australia has now cosigned a letter of understanding with APEMC in Singapore and a Technical
Committee with a mixture of EMCSA members and international representation.
APEMC will be significant event with expectations of greater than 300 delegates attending based on previous
events around Asia. It is not one to be missed. As such we will not be holding our local Symposium in 2012 and
2013.
We still intend as many CPD opportunities as can be organized. I look forward to meeting many of you this year
and hope that we can provide the services that you need.
Mark Mifsud
DISCLAIMER: The material in this newsletter is provided for information only. No responsibility of any form
of contractual tortuous or the liability is accepted from decisions made on the basis of the information
contained herein. Nothing contained in this newsletter is intended nor should be interpreted as being
engineering advice. Views expressed in articles do not necessarily represent EMC Society policy.
EMC Society of Australia Newsletter
3
2012 Student Paper Competition
Prize: $1000 for the best paper
The EMC Society once again invites Tertiary students to prepare a paper on any aspect of EMC technology .All
papers will be considered for publication in the EMCS Newsletter.
Conditions: The Entrant must be a student studying towards a recognized Award from an Australian Tertiary
Institution.
The paper should be the student’s own work, and should carry acknowledgements where others have
contributed. There is no set format for papers, but the requirements of professional institutions such as IE Aust.,
IEEE and IEE may be taken as a guide.
All papers must be received by 8th October 2012. Electronic submission is required and a confirmation of
receipt will be sent. Papers should be sent to enquiries@emcsa.org.au and should be in MS Word or Adobe pdf
format. Authors must prepare all graphics with a view to clearly communicating the information when printed in
black and white.
The National Council of the EMC Society will be responsible for judging the papers, and the Council’s decision
will be final. No correspondence will be entered into.
Further enquiries: enquiries@emcsa.org.au
Society News
In December 2011 Kingsley McRae successfully completed the
Advanced Management Program at the University of Chicago Booth
School of Business. Kingsley completed the program along with 22
accomplished international senior executives from a wide variety of
industries including aerospace, banking, consulting, engineering,
financial management, healthcare, insurance, manufacturing, mining,
and utilities.
The Advanced Management Program is suited for the unique needs
of senior executives responsible for enterprise leadership and
strategy. Participants engage in an active, experiential learning
environment aimed at helping them lead their organizations towards
growth in a rapidly evolving business landscape. The Advanced
Management Program is the only program offered for senior
executives that allows them to customize the content around their
personal development goals and business interests.
Congratulations Kingsley!
APEMC 2013
The Asia Pacific International Symposium on Electromagnetic Compatibility (APEMC) will be staged in
Melbourne, Australia in May 2013.
4 EMC Society of Australia Newsletter
February Presentation
The EMC Society hosted its first presentation this year in February at the IE Aust Building in Melbourne.
The presentation ‘Decoupling PCB’s for EMC and Functionality in the Real-World’ was given by Dr Bruce Archambeault
from IBM in Research Triangle Park, NC. Dr Bruce Archambeault is currently a member of the Board of Directors for the
IEEE EMC Society and a past Board of Directors member for the Applied Computational Electromagnetics Society
(ACES). He has served as a past IEEE/EMCS Distinguished Lecturer and Associate Editor for the IEEE Transactions on
Electromagnetic Compatibility. He is the author of the book “PCB Design for Real-World EMI Control” and the lead
author of the book titled “EMI/EMC Computational Modelling Handbook”.
Over 38 participants had a unique opportunity to enjoy inspiring and well presented talk on how to analyse decoupling
capacitors for noise control in PCBs. Bruce has described various real-world of measurements and simulations to
demonstrate the optimal decoupling strategy.
EMC Society of Australia Newsletter
5
EMC Society chairman is thanking Bruce and handing a gift after the presentation.
APEMC Symposium 2013 - Melbourne
Franz Schlagenhaufer
This Newsletter has reported about the Asia Pacific International Symposium on Electromagnetic Compatibility
(APEMC) in the past, and readers will be aware that this event will be staged in Melbourne, Australia in May
2013. It is also mentioned in the Chairman’s message in this issue.
APEMC Symposia are major EMC events and in the same league as EMC Europe or the IEEE EMC Symposia.
They bring together EMC experts from all over the world, with certain emphasis on the Asia-Pacific region, and
also try to balance between academia and industry. The technical program includes regular paper sessions,
poster sessions, workshops and tutorials, an industry forum and a trade exhibition.
The EMC Society of Australia is the official host of the APEMC Symposium 2013 and has formed a Conference
Organizing Committee consisting of Franz Schlagenhaufer as Chair, Paul Kay as Secretary and Kingsley McRae
as Treasurer. Technical Chair and Co-Chair are Alireza Baghai-Wadji, and Bill Radasky. Committee members,
at this time, are Gordana Felic, Mark Mifsud and Chris Zombolas. The Technical Program Committee will be
the same as for previous APEMC Symposia to guarantee consistency and a high level of quality.
The EMC Society of Australia had organized its own annual Symposia for 10 years, with the events in Adelaide,
Melbourne and Perth providing valuable experience, albeit the APEMC 2013 will be on a much bigger scale.
But the National EMCSA Symposia also gave confidence that Australia can contribute to the APEMC 2013 in
respect to technical papers and delegates. After all, it would be a shame if the host country would only be seen
as the organizer, but not be a significant part of the technical content as well.
6 EMC Society of Australia Newsletter
Testing Ourselves
EMC and Propagating Fields (The Answer)
Mark I. Montrose
Montrose Compliance Services, Inc.,
2353 Mission Glen Drive, Santa Clara, CA 95051-1214 USA
E-mail: mark@montrosecompliance.com
In the last issue of this magazine, a quiz was given to
test our skills as EMC engineers. This quiz dealt with
calculating or measuring emissions generated on a printed
circuit board (PCBs) relative to EMC regulatory
requirements. This is highly complex problem with many
variables, and for the EMC engineer, another day at the office.
The Question
Determine the magnitude of a propagated field
measured by an antenna. Determine if the RF field
developed by the printed circuit board inside an enclosure
complies with FCC or CE (Conformity Europe) Class B
regulatory requirements, and at what frequencies one
would observe the signal (Note that Class A and B
devices are those that are marketed for use in
commercial/industrial/business and home environments,
respectively; Class B limits are more stringent than Class A
limits). Also, determine the probable source location on the
printed circuit board where the radiated field is being
generated.
1.
The antenna is located at a distance of 1 m from the
system being tested.
2. There is a 125 MHz crystal and two oscillators; 25
MHz and 400 MHz.
3. The processor has a 1:4 PLL using the 25 MHz
oscillator signal as input.
4. The processor has a data-book typical value of 5A/800
ps associated to the dI/dt of the core circuitry.
5. There are multiple clock outputs from the processor, all
at various harmonics of the three input frequencies.
6. The routed transmission-line length of all clock traces
is 11.43 cm (4.5 inches).
7. The values of decoupling capacitors sprinkled
throughout the design are 100 nF, 10 nF, and 1 nF
(Hint: calculate the anti-resonant frequencies
developed to see if a harmonic of any clock source
exists at these frequencies).
8. There is an open-frame 500 W switching power supply
operating at 200 kHz without a secondary line filter
and three-wire power cord that includes a ground
terminal.
Repeat the above calculations for 3m and 10m to
determine if the signals measured follow typical
extrapolation factors, taking into consideration the
measurement uncertainty value of the antenna.
Discussion
Welcome to the field of electromagnetic
compatibility (EMC), where if one accidentally solves an
EMI problem as a designer, they may be transferred to
the compliance department since they must be a guru,
forever ending their career as a design engineer. To
solve the quiz, one must think in both the time and
frequency domains, a skill rarely mastered by design
engineers. If the EMC engineer has an EMI problem, do
they use an oscilloscope or a spectrum analyzer to isolate
and fix the problem?
As an EMC consultant, I prefer the oscilloscope,
since this tool allows me to see what a digital signal
looks like on a transmission line (a.k.a., a trace) to
determine the quality or signal integrity of a transmitted
wave in the time domain. A spectrum analyzer only
identifies an area where an RF signal may be present
using a tr ans duc er or field probe. The analyzer
“cannot” locate the actual source of energy development.
Due to how the printed circuit board (PCB) may be
manufactured, which includes distance spacing between
traces and planes (stackup configuration), flux coupling
(a.k.a., crosstalk), along with other losses present in the
board material, we can have a signal integrity problem. A
via may be the propagating source of EMI (antenna) and
not the transmission line, yet we focus on clock traces
and their lengths as antennas or the radiating
mechanism. How do we isolate a problem area with a
spectrum analyzer, especially if flux coupling occurs
internally to multilayer PCB (stripline routing)? What if
common-mode radiated EMI is from the silicon package
located on the outer layers of the assembly and has
nothing to do with PCB layout?
Generally, an EMC engineer must solve this
complex problem without knowledge of how the system
works (or even what it does), the type of digital
components provided, have in their possession a
schematic (assuming they understand advanced digital
design and technology being used and how to read the
schematic), or the actual PCB artwork along with
software to view the layout (not a Gerber file). There are
no datasheets on critical components or filters provided
along with a host of other unknowns.
The most common equations to determine the value
of a magnitude of the propagating RF field are given
below. Extracting the numbers given in the quiz, one
can easily determine the value of the E field, but is the
answer correct? For a signal to radiate, some form of
antenna structure must be present, either a trace or an
interconnecting cable. EMI is created from currents
flowing between components. A small loop antenna is
one the dimensions of which are smaller than a quarter
wavelength (λ/4) at a particular frequency of interest.
The maximum electric field strength from a loop
antenna in free space is:
EMC Society of Australia Newsletter
(1)
7
where A is the loop area in c m 2 , f is the frequency
MHz, I s is source current in mA, and r is the distance
from the radiating element to the receiving antenna.
The differential-mode radiation from a cable
affixed to the PCB with a ground reference is given by:
7.
8.
(2)
The common-mode radiation from a cable affixed to
the PCB with a ground reference is:
E=1.27*10-6(fLIs) 1/r _ [V/m]
(3)
The Answer: It Depends!
Now for the fun part: In reality, any number you
mathematically calculate to solve the quiz will be incorrect.
There is no "solution." The correct answer for all possible
permutations is: "It depends!" It depends on:
1. What is the noise-voltage bounce present on either
the power/return (ground) plane? Are we observing
radiation from the edges of the board, or is EMI
being propagated from the silicon packages and not
from any traces or interconnects provided?
2. What are the losses in transmission-line routing and
their effect on signal integrity? Poor signal integrity
is usually the cause of EMI. For example, the
voltage magnitude of overshoot during ringing due
to poor termination is generally the magnitude of
common-mode EMI developed, which in turn may
be the source EMI generation. One must use an
oscilloscope and not a spectrum analyzer to identify
if a transmission line is an area of concern that
needs to be addressed.
3. Is the antenna located in the near or far field at a
frequency of interest? At 1 m, we are in the near
field for the quiz, and signals measured below 300
MHz are invalid for compliance purposes.
4. Is the propagating field in the common- or
differential-mode? Are we measuring only the E
field, the H field, or the TEM field?
5. Is the PCB a four-layer or a 24-layer stackup? If
microstrip traces are present, the transmission line
may be the radiating antenna. If stripline routing is
used and flux coupling occurs between traces and
adjacent planes, how does this internally generated
EMI propagate to the outside world?
6. What about the decoupling capacitors mentioned in the
quiz? In reality, the values of the capacitors and their
self-resonant and anti-resonant frequencies are useless
information when attempting to solve this problem. It
was provided to throw the problem solver into a state
of confusion. Decoupling capacitors lowers plane
impedance, which in turn minimizes plane noise. It is
impossible to know what the self-resonant frequencies
of the capacitors are and, since we have no idea of what
8 9.
the lead or loop inductance is, how the components are
mounted onto the PCB, whether we are using surfacemount or through-hole mounting pads with or without
microvias, long or short breakout trace lengths, and the
like, we cannot calculate self-resonant frequencies.
Is RF energy created from the silicon components
themselves, the trace routing, or cable interconnects?
Is the unit in a metal case or a plastic enclosure? (This
information was not provided in the problem, only that
an enclosure was used).
Power supplies generally create low-frequency EMI,
measured as line-conducted emissions, and these are
rarely the primary source of high-frequency radiated
EMI. The quiz implied a high-frequency problem.
When trying to extrapolate a measured field between 1, 3,
and 10 meters, it is impossible to achieve an accurate
extrapolated value due to measurement uncertainty of the
ground-plane construction, antenna height, turntable angle,
electromagnetic scattering from metallic objects nearby,
whether we are in the near- or far-field at a particular
frequency of interest, plus the normalized site attenuation
values being accurate at different antenna distances.
Conclusion
Enjoy the field of EMC. Measuring propagating fields is
easy. Understanding the source of where the RF energy is
generated and how this field is propagated ensures job
security for many, especially if we are dealing with
unintentional radiators. Should we even care about the
signal measured by an antenna, especially if it does not
cause harm to the environment? Remember, the above quiz
has no solution. The answer "it depends" illustrates why
EMC engineers have a difficult time trying to achieve
compliance when there are many unknowns.
Mark Montrose is principal
consultant
of
Montrose
Compliance Services, Inc.,
located in Santa Clara,
California (USA).
His
expertise includes design,
testing, and certification of
information technology and
industrial, scientific, and
medical equipment (ISM) and
is an ISO 17025 assessed
EMC test laboratory.
He
specializes in the international
arena for the European EMC
Directive. Mark graduated
from California Polytechnic State University, San Luis Obispo,
California, with BSc degrees in both Electrical Engineering and
Computer Science. He completed his MSc Degree in Engineering
Management from the University of Santa Clara, Santa Clara,
California. He is very active within the IEEE, having served as a
member of the IEEE Board of Directors (Division VI Director),
IEEE EMC Society Board of Directors, and President of the IEEE
Product Safety Engineering Society. Mark has authored bestselling EMC reference and textbooks published by Wiley/IEEE
Press, all sponsored by the IEEE EMC Society.
This article, with modification, was previous published in:
IEEE Antennas and Propagation Magazine, Vol. 50, No. 4, August
2008.
EMC Society of Australia Newsletter
Investigation into Field and Surface Current
Intensification for Whole Aircraft Testing in a
TEM cell
Andrew J. Walters, Chris Leat and Craig Denton
Defence Science and Technology Organisation
Air Operations Division
PO Box 1500, Edinburgh, South Australia 5111
Email: andrew.walters@dsto.defence.gov.au
Abstract— Transverse Electromagnetic (TEM) cells offer
one solution to the problem of EMV testing of whole vehicles
at lower frequencies. This paper discusses computational
electromagnetics (CEM) modelling used to investigate the
levels of field intensi- fication and skin current distribution
when testing an aircraft using a TEM cell. Comparisons are
made between a simulated aircraft in the DSTO TEM cell,
Open Area Test Site (OATS) and the free space case. The
results are discussed with respect to implications for future
TEM cell designs.
2.26 m. The tapered sections are 1.114 m long and the
feed points of the septum are offset 0.29 m from the cell
wall.
In this paper we present results which validate our
compu- tational model of the DSTO TEM. The technique
is then used to model the Macchi aircraft inside the TEM
cell, from which the results are compared with those
obtained from models of the aircraft in free space and on
an OATS.
II. MODEL VALIDATION
I. INTRODUCTION
Electromagnetic Vulnerability (EMV) testing of whole
ve- hicles continues to be an important research area for
DSTO. A reverberation chamber (RC) was built and
tested for this purpose and works well at frequencies >30
MHz, where mode density is high. At frequencies lower
than this, DSTO currently uses an open area test site
(OATS) and bulk current injec- tion. The limitations of
the OATS technique, restrictions on spectrum use etc.,
have spawned a requirement to investigate alternative
techniques. In the literature TEM cells have been
proposed for whole vehicle testing both in the pure form
[1], and in hybrid configurations with an RC [2].
Investigations into TEM cell design is part of a project
aimed at extending the operation of the DSTO RC for
frequencies below 30 MHz. The limitations of the pure
TEM cell design lie within the confined test volume,
frequency limits due to the appearance of higher order
modes, and single polarization restrictions. Other methods
of constructing TEM cells have been proposed and
modeled in which improved performance has been
obtained through changes in septum design and loading
methods. For example, Carbonini [3] reports on a cell with
double polariza- tion and balanced wire septa, resulting in
optimization of the
test volume dimensions.
The DSTO TEM cell is a modified “Crawford style”
cell [4], [5] which has been studied in order to create a
baseline for alternate designs. The physical TEM cell that
has been measured and modeled was intended to be a
scale model of what could be implemented in the existing
RC, and its proportions are thus based on this. The outer
dimensions transverse to the propagation direction are
2.335 m by 1.27 m, and length of the parallel section is
The MoM model and measurement of the TEM cell
has been previously compared by the authors [5]. This
initial study showed good agreement between the two sets
of TEM cell results. At 79.8 MHz however, a large
resonance peak was seen in the model data and not in the
measurements. On repeating the measurements for a
restricted range it was found that an equivalent resonance
peak also existed in the measurements. The peak, at
approximately 80 MHz is the TE011 mode. The measured
and modeled peaks differed slightly in frequency, and
the relatively coarse sampling initially used [5], had
missed the very narrow band peak in the measurements. A
much finer sampling has now been adopted of 100kHz
for both measurement and modeling, and the results are
displayed in figure 1. The figure shows total electric field
generated at a central point for 1 W of nett input power.
Fig. 1. Comparison between measurement and model results
for the DSTO TEM cell.
EMC Society of Australia Newsletter
9
The desired TEM mode is present below 79.8 MHz
and between the peaks at 79.8 MHz and 123 MHz. It is
seen that the measurements and model agree very well
upon the level of field for the TEM mode with a
discrepancy of less than 2 dB. Above the 123 MHz peak,
it is not apparent what the relative contributions are from
TEM and resonant modes. Total field levels agree well,
however. It is clear that all the resonances present in the
model are present in the measurements with some
disagreement in frequency by approximately 2.5 MHz.
Some resonant peaks are seen in the measurements
below 79.8 MHz, which disagrees with the theoretical
minimum frequency for resonance in a cavity of this size,
and with the numerical model. These peaks are due to the
use of the E field probe together with third harmonic
distortion in the amplifier. For example, the amplifier
when excited at 41 MHz, is also producing some 123
MHz in its output. The 123MHz signal excites the 123
MHz cavity resonance which is detected by the E field
probe as part of the total field, with the result that it
appears, incorrectly, at 41 MHz.
III. TEM CELL APPLICABILITY TO WHOLE
AIRCRAFT EMC TESTING.
Fig. 2.
Model of the Macchi aircraft in free space.
Fig. 3.
Model of the Macchi aircraft on an OATS.
Fig. 4.
Model of the Macchi aircraft in the DSTO TEM cell.
Hence forth the TEM cell model dimensions have been
scaled up by a factor of 4.7 to represent the intended size
of the cell for whole aircraft testing. Therefore the TE011
resonance at 79.8 MHz mentioned above occurs at
79.8/4.7 = 16.98 MHz in the scaled up cell.
A. FEKO Models
The Macchi aircraft was acquired in 1967 for use
with the Royal Australian Air Force (RAAF) and Royal
Australian Navy (RAN), where it served as mainly a
trainer aircraft. Now out of service, a Macchi has been
obtained by DSTO for its EMC research program. We
have therefore used it as the test subject to assess and
develop the applicability of whole vehicle EMC testing in
a TEM cell. Three different cases were considered in our
computational model investigations of the EMV test
methods:
• A Macchi in free space for baseline purposes
• A Macchi on the OATS to test existing techniques
• A Macchi in the vertically polarised DSTO TEM
cell. The three method of moments (MoM) models are
shown in Figures 2, 3 and 4 respectively.
The Macchi was meshed in an engineering modeling
tool,FEMAP, from a CAD file and then entered into
FEKO. FEKO [6] is a commercial electromagnetic
software package capable of hybrid UTD/MoM operation.
We used the MoM capability, which is based on the well
known Rao-Wilton- Glisson basis functions. The TEM
cell and OATS ground plane are both constructed in
FEKO from triangular surface elements. In the free-space
and OATS environments a standard FEKO plane wave
source was used. For the TEM cell, narrow triangular
plates were used to connect each septum end to its
adjacent outer shell region. This construction mimics the
coaxial connectors at the ends, the shield of which is
connected to the outer chamber, and the inner of which is
connected to the septum tip.
10
One wire was then driven with a voltage source, and the
other was loaded with a 50Ω resistance.
In order to compare the three Macchi model
configurations, we needed to calibrate the TEM cell and
OATS to the free space case. In free space we set the
plane wave source to
1 V/m. The driving voltage required in the TEM cell was
calculated by finding the average field strength for a
volume inside the empty cell at 10 MHz. Using this
average field, the driving voltage was scaled up to
produce an average field strength of 1 V/m. This voltage
was found to be 4.6 V. For the OATS, only the case
where the plane wave source is horizontally polarised has
to be calculated. This is due to the boundary conditions
imposed by the horizontal ground plane. The electric
field was calculated 2 m above the centre of the ground
plane for all the frequencies. These values were used as
scaling factors at the various frequencies for the results
obtained when the Macchi was present. This reflects
normal OATS calibration practice in the field.
B. Electric Field Intensification
TEM cell design calls generally for minimum size due
to the need to keep resonance frequencies high, and to
reduce required input power levels. Additionally, in
DSTO’s case, a desire exists to modify the existing RC.
Thus DSTO is pushing the limits of useable TEM cell
volume, as a typical jet fighter occupies a considerably
EMC Society of Australia Newsletter
greater fraction of the TEM cell volume than is generally
felt to be ideal. The concern arises, as to what could the
effects be, of the proximity of the aircraft appendages to
the TEM cell walls. An obvious possibility is the
intensification of electric field strengths in these areas, as
charge accumulation on aircraft appendages leads to
induction of corresponding charges on the TEM cell
surfaces and vice versa. Note that it is of no use to
compare the fields around the aircraft to 1V/m, as we
are considering the total field, not the incident field.
Even in free space intensification of field strengths will
occur near terminal points of the airframe. Near electric
field strength is the determining factor in coupling to
projecting conductors including monopole antennas,
hence it is important the test method produces realistic
levels.
To investigate the electric field intensification in the
TEM cell and OATS compared to free space, a series of
field observation points were located 20 cm from key
points on the Macchi aircraft (see Figure 5). There is also
one directly below the cockpit which is not shown in the
figure.
Fig. 5.
Electric field observation points around the Macchi.
For the Macchi in the TEM cell and in free space, the
electric field strength at each of the nine points is
calculated for frequencies 1MHz to 36 MHz at 1 MHz
steps1 . To maximise separations of the Macchi from the
TEM cell walls, the cell was rotated 45 degrees in the xy
plane with respect to the Macchi’s centre. This requires
the plane wave sources in the OATS and free space cases
to be at 45 degrees to the Macchi also.
The TEM cell, with the septum oriented horizontally
above the Macchi, produces a vertically polarised electric
field. The plane wave sources were therefore given a
vertical polarisation also, in order to match the TEM
cell configuration. The electric field strength was
calculated at the designated points for the Macchi
aircraft in the three environments. Electric field
strength intensification was computed by dividing both
the TEM cell and OATS fields magnitudes by the free
space magnitudes. These ratios are plotted on a dB scale
in figures 6 and 7 and identified as ‘E-Field
intensification’. Each subplot in the two figures relates
1 Since the RC works down to 30 MHz, 36 MHz was chosen as the
upper frequency to provide some overlap.
to a separate field observation point. The relative near
electric field strengths plotted in figures 6 and 7 provide
a measure of the particular techniques ability to reproduce
the free space electric field conditions seen by the
Macchi aircraft. 0 dB is the ideal.
The field intensification results show a wide range of
per- formance by the two testing methods. In the OATS
case there is little field strength deviation from the free
space results, ± 5 dB, for the wings, nose and
horizontal stabilizers. The fuselage and cockpit results
show a slightly higher variation under testing almost
down to -10 dB. There is however in all cases but one,
increased field intensification seen around 12 MHz
corresponding to the natural resonance of the Macchi
airframe against the ground plane. For the ‘above cockpit’
observation point only a small variation is seen at 12
MHz unlike the other points. The results for the vertical
stabilizer show the largest under test for the OATS down
to -20 dB. This is a surprising result since it is expected
that for a vertically polarized field the field strengths
around the vertical stabilizer in the OATS case should be
similar to that for the Macchi in free space. The results
show that generally the TEM cell performs differently
than the OATS. All the observation points except the
‘below cockpit’ point trend towards over testing with
intensification as high as 40 dB. As mentioned earlier,
ap- pendage proximity to the TEM cell walls and septum
may cause additional field intensity. Like the OATS
results, the Macchi airframe 12 MHz resonance is also
seen is some of the TEM cell results. However in
contrast to the OATS results for the vertical stabilizer,
the TEM cell performs better with an over test
averaging 5 dB. The vertical stabilizer is the part of the
aircraft that comes the closest to the TEM cell septum and
so it is logical to assume that this point would exhibit the
greatest intensification, the fact that it does not
demonstrates the non-intuitive nature of this type of
study.
As well as proximity, the second factor seen in all
the TEM cell results is field intensification caused by the
natural resonances of the TEM cell cavity loaded with the
Macchi aircraft. This is by far the larger of the two hurdles
to overcome in order for the TEM cell to be a viable
EMV test method for whole aircraft.
C. Surface Current Investigation
For EMV testing at low frequencies, the most
important aspect is that of surface currents, produced by
the aircraft being exposed to electric fields. It is these
surface currents which induce currents on the cables
turn
creates
inside the aircrafts skin which in
undesirable behaviour within the aircraft’s avionics
systems. In order to thoroughly test the applicability of
the TEM cell methodology to EMV testing, we
therefore studied the surface currents induced on the
Macchi airframe. The aim was to compare the surface
configurations, free space, OATS and TEM cell. The
MoM method of calculation provides the surface current
for each triangle within the surface mesh of the
EMC Society of Australia Newsletter
11
(a) Left Wing
(b) Right Wing
(c) Nose
(d) Vertical Stabilizer
(e) End of Fuselage
Fig. 6.
12
(f) Below Cockpit
Electric field intensification relative to the free space case for the Macchi in the TEM cell and on the OATS.
EMC Society of Australia Newsletter
(a) Above Cockpit
(b) Left Stabilizer
(c) Right Stabilizer
Fig. 7 Electric field intensification relative to the free space case for the Macchi in the TEM cell and on the OATS. Cont …
computational model. To minimise the volume of data
used for the comparison, a select number of surface mesh
triangles were chosen as current observation sites. Sites
were chosen to relate closely to the field observation
points described in the last section. One site was chosen
on each wing, nose, cockpit, horizontal and vertical
stabilizers. Their positions are shown in figures 8 and 9.
Fig. 8. The Macchi MoM model showing current observation
triangle 1.
TABLE I
PLANE
WAV E S O U R C E C O N FI G U R AT I O N S U S E D F O R F R E E S PAC E
A N D OATS.
Direction φ
(Degrees)
0
45
0
90
Polarisation η
(Degrees)
0
0
90
90
For the Macchi in free space and on the OATS, several
model incident field configurations were considered and
then the results combined to produce a more representative
baseline for comparison in each case. The plane wave
source orienta- tions and directions used are listed in table
I and shown in figure 10. Note that θ = 90◦ for all cases.
A set of surface current results were obtained for each
source orientation at frequencies 1MHz to 36 MHz in 1
MHz steps. For a particular case, free space or OATS, the
maximum current density is calculated at each frequency
point over all polarisations and directions using the
following expressions:
EMC Society of Australia Newsletter
13
Fig. 10. Orientation of the FEKO plane wave source. φ represents
the position of the source with respect to the x-axis in the x-y plane. η
represents the polarisation of the source. Note that the Macchi aircraft is
positioned with it’s fuselage running along the x-axis.
Fig. 9. The Macchi MoM model showing current observation triangles 27.
J
(n)
frees space
( f ) = max J
max
i =1,4
(i ,n )
free space
(f)
(n)
(i ,n )
J OATS
( f ) = max J OATS
(f)
max
i =1,4
(1)
(2)
where J is the current density in A/m, i represents the 4
different polarisation/direction configurations of the
source (see table I), f is frequency, and n=1 to 7
corresponds to the 7 observation sites (figures 8 and 9).
The results for the 7 observation triangles are used to
calculate the current intensification relative to the free
space case using (3) and (4).
J
(n)
TEM / Free
( f ) = 20 log10
(n)
J TEM
(f)
J
(n)
free space
(3)
(f)
max
J
(n)
OATS / Free
( f ) = 20 log10
(n)
J OATS
(f)
max
(4)
n)
J (free
space ( f )
max
where the current intensification is given in dB. The results
are plotted in figure 11. Note that any values above 0 dB
indicate an over-test condition where the surface currents
are higher than the free space case, and values below the 0
dB point indicate an under-test.
In the subplots of figure 11 three curves are plotted,
‘TEM- Free space’ for Φ = 45◦ and φ = 0◦ 2 and ‘OATSFree space’. Over all seven plots thre is a great degree of
difference between the TEM cell plots and with the
OATS.In general the TEM results exhibit an under test
for frequencies below 27 MHZ, getting as low as -30 dB
in some cases. Above 27 MHz the results generally show
an over test corresponding to the area containing the
natural resonances of the TEM cell. For Φ= 450, the TEM
results show less variation than for Φ = 00 results. This is
likely due to the greater distance between aircraft
appendages and the cell walls for the 450 case. However
this leads to a greater degree of under test than the 00 case
as is seen in figures 11b and 11d in particular.
In figure 11 we see that the Macchi on the OATS
also has deviations from the conditions produced in
free space by up to 20 dB for the vertical stabilizer
(figure 11a), at frequencies below 15 MHz. However above
15 MHz the OATS performance is good, only showing
deviations up to 5 dB. Over the most part the OATS results
show an over-test situation for each of the sites compared
with the TEM Cell. However for both the TEM cell and
OATS techniques, improvements can be made by adapting
the input powers as a function of frequency to allow for the
deviations from the free space case.
Consider the Macchi in the TEM cell and on the OATS.
At each frequency f we take the average of the relative
surface currents. These averages then represent a factor
which can be applied to scale the input power levels which
will then bring the results closer to the free space
expectations. The scaled results were obtained using the
following expressions:
N
(n)
Σ J TEM
/ Free ( f )
(m)
(m)
n =1
J TEM
/ Free ( f ) = J TEM / Free ( f ) −
Scaled
Unlike the E-field intensification work, the Macchi was positioned in
two orientations inside the TEM cell.
2
14
EMC Society of Australia Newsletter
N
(5)
(a) Observation Site 1. Vertical Stabilizer
(b) Observation Site 2. Nose
(c) Observation Site 3. Cockpit
(d) Observation Site 4. Left Wing
(e) Observation Site 5. Right Wing
(f) Observation Site 6. Left Stabilizer
(g) Observation Site 7. Right
stabilizer
Fig. 11.
Surface current intensification
(n)
J TEM
/ Free ( f ) for TEM+Macchi (0◦
and 45◦ orientation) and
(n)
J OATS
/ Free ( f ) for
OATS+Macchi.
EMC Society of Australia Newsletter
15
N
(n)
Σ J OATS
/ Free ( f )
(m)
(m)
n =1
J OATS
/ Free ( f ) = J OATS / Free ( f ) −
Scaled
N
(6)
where m = 1 to 7 represents the observation sites, N=7 is the
total number of observing sites and the current
intensifications, J , are all in dB. It must be noted that this
procedure cannot, however, diminish the spread in relative
current levels between the 7 triangles. Figure 12 shows the
current intensification curves for all 7 observation triangles
after they have been adjusted in this manner.
dimensions, we see TEM behaviour in the region below 17
MHz and also between 17 MHz and 26 MHz.
We have also reported in this paper, a new metric for
measuring the performance of a loaded TEM cell and
OATS compared with free space, using field and surface
current in- tensifications. The results have indicated that
between the two techniques the OATS performs closer to
the free space case than the TEM cell. The TEM cell
suffers from restrictions on the volume available for testing
in addition to non-uniformity caused by natural resonances
of the cell’s cavity.
Future work will involve investigating ways of
increasing the useable test volume of the TEM cell as
well as ways to actively cancel the high order resonances.
One technique which has been reported in the literature is
the use of wires instead of a solid septum [7]. This
technique may provide gains in the size of the test
volume however we expect that a other methods will be
required to reduce the impact of the TEM cell resonances.
ACKNOW LEDGMENT
Fig. 12. Adjusted TEM+Macci surface current intensification
curves for all 7 observation triangles. This is for the 45 degree
TEM-Macchi orientation.
The results in Figure 12 show that once adjusted the
TEM+Macchi current intensification curves span
approximately from -10 dB to +10 dB. This is indicating
that the limiting factor for the TEM cell is the current
variation between observation sites across the Macchi
aircraft, therefore reducing the effectiveness of this
procedure.
The authors would like to thank the DGTA (Directorate
General Technical Airworthiness) for sponsoring the work
program on electromagnetic environmental effects on
aircraft. Stuart Thomson for assistance with meshing the
Macchi amongst other things and Kevin Goldsmith for
helpful dis- cussions.
REFERENCES
[1] R. L. Monahan, T. M. North, and A. Z. Xiong, “Characterization of
large tem cells and their interaction with large dut for vehicle
immunity testing and antenna factor determination,” Proceedings
IEEE EMC Symposium Seattle Aug 2-6, p. 245, 1999.
[2] M. L. Crawford, M. T. Ma, J. M. Ladbury, and B. F. Riddle,
“Measure- ment and evaluation of a tem / reverberating chamber,”
NIST Technical Note 1342 United States Department of Commerce.
[3] L. Carbonini, “A new transmission-line device with doublepolarization capability for use in radiated emc tests,” IEEE trans. on
EMC, vol. 43, no. 3, p. 326, 2001.
[4] M. L. Crawford, “Generation of standard em fields using tem
transmission cells,” IEEE trans. on EMC, vol. 16, no. 4, 1974.
[5] A. Walters, C. Leat, C. Denton, S. Thomson, and K. Goldsmith,
“Tem cell numerical modelling and measurement at the dsto,”
EMC 2003 Symposium Record 2nd Oct. Melbourne Australia, 2003.
[6] FEKO, EM Software and Systems-S.A. (Pty) Ltd,
http://www.feko.info.
[7] L. Carbonini, “Comparison of analysis of a wtem cell with standard
tem cells for generating em fields,” IEEE trans. on EMC, vol. 35,
no. 2, p. 255, 1993
Fig. 13. Adjusted OATS+Macci surface current intensification
curves for all 7 observation triangles.
Dr Andrew Walters is E3 Science
Team Leader, Airborne Mission
Systems, Air Operations Division,
Defence Science and Technology
Organisation in Edinburgh, South
Australia.
The OATS results once adjusted in the same way have a
span of around -8 dB to +8 dB as shown in figure 13. The
curves are also smoother, as would be expected due to the
absence of the numerous resonances found in the TEM cell.
However current variation between the observation sites
limits the benefit of the scaling process here also.
IV. CONCLUSION
In this study we have validated a computational electromagnetics model of the DSTO TEM cell using
measurement results. In addition we have shown the
importance of using the two techniques in tandem to
acquire a more accurate picture of the system. Considering
the empty TEM cell results scaled up to the RC
16
This article was previous published in:
The Proceeding of EMCSA Symposium, September 2004.
EMC Society of Australia Newsletter
EMC effects in integrated circuits: nonlinear
distortion
Jean-Michel Redouté
Electrical and Computer Systems Engineering, Monash University,
Clayton, VIC 3800, Australia
jean-michel.redoute@monash.edu
I. INTRODUCTION
Distortion is a common phenomenon in integrated
electronics: although the topic itself is well documented, it
remains a distrusted subject as well as continuous source of
concern during the design of analogue IC’s. As cited in
[8], distortion is nothing else but a deviation of the output
signal from the wanted waveform. Distortion occurs in
linear circuits (linear distortion) as well as in nonlinear
ones (nonlinear distortion). When conducted EMI is
injected into an arbitrary integrated circuit through one or
more pins, it obviously introduces a certain amount of
distortion. Keeping in mind that EMI does not necessarily
follow the signal path and that it may couple through and
between any parasitic path leading to an outside pin,
existing distortion analyses techniques are applicable as
such when designing EMI resisting integrated circuits. As
illustrated further on, different distortion types each cause
a different EMC circuit behaviour. To this end, linear and
nonlinear distortion needs to be considered separately.
This article will describe the effect of EMI caused
distortion in integrated circuits mathematically, and use a
case study to illustrate how these phenomena are taking
place at circuit level.
II. LINEAR DISTORTION
Linear distortion is the distortion which arises in purely
linear circuits, as soon as one or more linear components
exhibit a non-flat frequency response [8]. Consider as an
example a square wave which is applied at the input of a
R-C low-pass filter: the output of this R-C filter is linearly
distorted, because the high frequency sinusoidal
components are more attenuated than the low frequency
ones (Fig. 1). However, no new spectral lines are created in
the frequency spectrum: this is the basic characteristic of
linear distortion [6]. Linear distortion also appears in any
practical amplifier owing to the non-ideal gain and phase
variations as a function of the frequency. When EMI is
injected in a fully linear circuit, it behaves no differently
than any other wanted signal: as such, the interfering signal
is linearly distorted in the event that it has frequency
components which lie above the circuit’s cut-off
frequency. This linearly distorted EMI signal is then
superposed on the wanted signal(s) which are processed by
this circuit, hereby causing an unwanted ripple. This ripple
may distort the amplitude of wanted signals and may
equally impair the correct circuit’s behaviour (e.g. by
triggering false states in digital circuitry). Much more
importantly, this ripple may couple to neighbouring
circuits which may in turn exhibit a nonlinear behaviour,
causing nonlinear distortion.
III. NONLINEAR DISTORTION
When the main parasitic paths through which the EMI
couples in a particular integrated (sub)circuit are identified,
measures can be taken in order to filter the resulting EMI
induced ripple. Decoupling capacitors, linear filters and
other circuit techniques (like using opamps with a high
power supply rejection ratio in order to shield the wanted
signals from electromagnetic noise which is present on the
power supply rails) must be used to filter the EMI before it
reaches and mixes with sensitive and nonlinear circuit
nodes. Failing to do so results in nonlinear distortion [1].
Nonlinear distortion arises in nonlinear circuits, and
amounts to the distortion of the signal amplitude as well as
to the position of spectral components. Two different
nonlinear distortion types are identified: harmonic and
intermodulation distortion. Harmonic distortion is derived
and explained here below.
Consider a memory-less, weakly nonlinear system, of
which the output signal (vo) is related to the input signal
(vi) as follows [3]:
(1)
Assume that the input signal is a sinusoidal EMI signal,
expressed as follows:
(2)
Substituting (2) in (1), and performing basic trigonometric
operations yields:
(3)
Equation (3) illustrates that when nonlinear circuits are
excited with a single sinusoidal signal, the frequency
spectrum of the output contains a spectral component at the
original (fundamental) frequency, as well as spectral
components at multiples of the fundamental frequency
(harmonic frequencies).
This type of distortion in commonly referred to as harmonic
distortion, since the distortion components manifest
themselves at harmonics (multiples) of the fundamental
frequency [6]. Harmonic distortion is particularly harmful
EMC Society of Australia Newsletter
17
because the harmonic components associated to the
nonlinear distortion of a sinusoidal out-of-band EMI signal,
may appear in the signal band, even if the EMI frequency
band is not interfering with the wanted signal band. From
then on, filtering or removing interfering EMI harmonic
component(s) becomes very difficult.
Moreover, observe in (3) that a component at DC
appears as well. This DC component depends on the evenorder nonlinear behaviour, as calculated in [8]: this is not
very surprising, since even-order harmonics are related to
asymmetrical behaviour (resulting in a shift of the DC
value). This DC component constitutes a serious concern
for EMI resisting circuit design. Indeed, the DC shift
phenomenon which arises when this DC component is
accumulated (e.g. in a capacitor), is extremely harmful
because the correct DC operating region of a given circuit
may radically change under influence of an interfering
EMI signal: in extremis, particular circuit nodes as well as
subsequent stages may be forced into saturation or
complete cut-off. This process of accumulating the DC
component is called charge pumping [5], while DC shift is
the result of the shift in DC bias. Because DC shift is a DC
effect, it is not possible to filter or simply nullify it once it
has taken place. Consequently, in order to increase the
immunity of the IC in question, two approaches can be
followed.
•
First, the EMI disturbance can be filtered in order
to prevent it from affecting adversely the correct IC
operation. However, it is important to filter EMI in a linear
way, meaning that they should be intercepted before
reaching and interfering with nonlinear circuit nodes.
•
Secondly, the bandwidth of the circuit can be
increased, so that it lies above the most significant EMI
induced harmonics and intermodulation products,
preventing the process of accumulating the DC value.
Nonlinear distortion is equally identified as rectification:
this term originated in the first radio detectors that used a
nonlinear element (like a small piece of galena crystal) to
rectify an AM modulated radio signal [Phi80]. Two types
of rectification are commonly distinguished in the
literature: soft and hard rectification [6]. Soft rectification
means that the DC operating point shift is not large enough
to fully cut-off the device, while hard rectification
periodically cuts of the device when EMI is injected into
the circuit node in question. This corresponds respectively
to the weak and strong nonlinear distortion [8], [6].
Assume that an EMI AC current iemi is superposed on the
DC voltage of IIN. The interference iemi is sinusoidal, and
defined as follows:
(5)
The total input current is then represented as:
(6)
The total gate-source voltage is expressed accordingly as:
(7)
The modulation index (m) is defined as the ratio between
the EMI amplitude and the DC bias current:
(8)
As long as m < 1, the amplitude of the EMI is smaller than
the bias current IIN. In that case, the diode connected
transistor is always conducting a forward current. The
relationship between the amplitude of the EMI signal and
the magnitude of the input bias current is then expressed as
a function of m, meaning that (6) is rewritten as:
(9)
Substituting (9) in (7), the following expression for the
gate-source voltage is obtained:
(10)
As long as the modulation index m is smaller than 1, Taylor
series can be used to expand expression (10) [2]. This
yields following expression
(11)
Observe that the nonlinear Vgs signal has been expanded
into a power series. The mean value over time of the gatesource voltage is now equal to [2]:
CASE STUDY: DIODE CONNECTED NMOS
TRANSISTOR
Consider a diode connected NMOS transistor, which is
biased by a DC current source IIN (Fig. 2.a). Assuming
that the NMOS transistor is biased in strong inversion, and
using first order MOS transistor formulas, the gate-source
voltage of this transistor is equal to [7]:
(4)
18
(12)
Previous expression shows that the average value of Vgs
shifts downward owing to the EMI. The visual
representation of this effect is sketched in Fig. 2.b. Observe
that owing to the EMI disturbance iemi, the operating point
moves from A to B. This illustrates that DC shift is taking
place in this circuit, and that the latter is at risk of being debiased by nonlinear distortion of electromagnetic
interference.
EMC Society of Australia Newsletter
IV. CONCLUSIONS
It is clear that EMI induced DC shift is the worst appearing
EMC phenomenon at integrated circuit level, disrupting the
sound operation of IC’s, and sometimes even de-biasing
them completely. It is therefore of paramount importance to
identify the parameters which induce DC shift. As has been
explained here above, the latter is generated by the
accumulation of asymmetrically rectified signals. In
principle, getting rid of nonlinear distortion ensures a DC
shift-free circuit operation. This is, however, easier said
than done. As discussed anteriorly, preventing
accumulation by increasing the bandwidth of the circuit (i.e.
not taking the average value of Vgs in the above case
study), decreases DC shift. However, since the bandwidth
is typically limited, DC shift can always occur in practice,
depending on the interfering frequencies: consequently,
filtering high frequency EMI disturbances before they reach
sensitive circuit nodes remains mandatory.
References
[1] F. Fiori and P. S. Crovetti, "Prediction of EMI effects in
operational amplifiers by a two-input Volterra series model", IEE
Proceedings on Circuits, Devices and Systems, vol. 150, no. 3, pp.
185-193, June 2003.
[2] J. Glyn, Modern Engineering Mathematics, Addison-Wesley
publishing company, second edition, 1996.
[3] Y. E. Papananos, Radio-Frequency Microelectronic Circuits
for Telecommunication Applications, Kluwer Academic
Publishers, 1999.
[4] V. J. Phillips Early Radio Wave Detectors, IEEE & P.
Peregrinus, 1980.
[5] J.-M. Redouté and M. Steyaert, "Current mirror structure
insensitive to conducted EMI", IEE Electronics Letters, vol. 41,
no. 21, pp. 1145-1146, October 2005.
[6] W. M. C. Sansen, "Distortion in elementary transistor circuits",
IEEE Transactions on Circuits and Systems II, vol. 46, no. 3, pp.
315â˘A ¸S325, March 1999.
[7] W. M. C. Sansen, Analog Design Essentials, Springer, 2006.
[8] P. Wambacq and W. Sansen, Distortion Analysis of Analog
Integrated Circuits, Kluwer Academic Publishers, 1998.
[9] A.Wieers and H. Casier, "Methodology and case study for high
immunity automotive design", Proceedings of the 15th Workshop
on the Advances in Analog Circuit Design, Maastricht, the
Netherlands, April 2006.
Figure 2: (a) Diode connected NMOS transistor - (b) DC shift in
the diode connected NMOS transistor.
Jean-Michel Redoute was born in
Antwerpen, Belgium, in 1975. He
received the degree of M.S. in
electronics at the University
College in Antwerp, in 1998, and
the degree of M.S. in electrical
engineering at the University of
Brussels (VUB), in 2001.
In August 2001, he started working
at Alcatel Bell in Antwerpen,
where he was involved in the
design of analogue microelectronic
circuits for telecommunications
systems.
In January 2005, he joined the ESAT-MICAS laboratories of the
Katholieke Universiteit Leuven as a Ph. D. research assistant. In
May 2009, he defended his Ph. D. entitled "Design of EMI
resisting analog integrated circuits". In September 2009, he started
working at the Berkeley Wireless Research Center at the
University of California, at Berkeley. In September 2010, he
joined Monash University as a senior lecturer.
Figure 1: Linear distortion in a R-C low-pass filter.
EMC Society of Australia Newsletter
19
Calendar of Events
May 13-16
SPI 2012, 16th IEEE Workshop on Signal Propagation on Interconnections
Sorrento, Italy
Antonio Maffucci
Email: maffucci@unicas.it
May 21-24
Asia Pacific EMC Symposium
Singapore
http://www.apemc2012.org
May 21-23
2012 ESA Workshop on Aerospace EMC
Venice, Italy
Filippo Marliani
http://www.hirf-se.eu
July 2-6
EUROEM 2012
European Conference and Exhibition on Electromagnetics
Toulouse, France
Jean-Philippe Parmantier
http://www.euroem.org
September 17-21
EMC Europe 2012
Rome, Italy
http://www.emceurope2012.it
November 6-9
CEEM 2012, 6th Asia-Pacific Conference on Environmental Electromagnetics
Shanghai, China
Prof. Gao Yougang
http://www.emc2012beijing.com
20
EMC Society of Australia Newsletter
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