A Tunable 3.9~7.1 GHz CMOS LNA for UltraWideband Wireless Communication
Yao-Chian Lin
Mei-Ling Yeh
Department of Electrical
Engineering National
Taiwan Ocean University
Keelung, Taiwan.
mason519@gmail.com
Department of Electronic
Engineering , St. John's
University, Tamsui,
Taiwan .
mlyeh@mail.sju.edu.tw
Abstract—A low-noise amplifier (LNA) with tunable output
matching network is designed for a frequency band 3.9 ~ 7.1
GHz. The LNA gain can be tuned by varying the control
voltage of varactor. The gain tuning range are 3 and 5.5 dB at
3.9 and 7.1 GHz, respectively. A maximum gain of 13.68 dB is
obtained. The LNA consumes 22.8 mW with a supply of 1.5 V.
The resistive shunt-feedback technique is used to design this
broadband LNA. The LNA is fabricating in 0.18um standard
CMOS process.
I.
INTRODUCTION
Recently, ultra-wideband (UWB) technology has
attracted a significant amount of research and development
activity [1]. UWB technology can provide a low power, high
data rate, low noise, and low cost solution for wireless
applications such as wireless personal area network (WPAN)
application. The most current proposal for such a standard
has target data transmission rates from 22 Mbps to 1320
Mbps with 2 individual bands of 3.1 -4.85 GHz and 6.2 -9.7
GHz. Low power consumption is also required for most
mobile applications.
To support the high speed of the data transmission rates,
the receiver front-end must be able to provide a simple and
low-cost solution to cover a bandwidth close to that
allocated by the FCC. Besides, it is a great challenge to
satisfy the uniform performance specifications over a large
frequency bandwidth. UWB uses the short pulse way to
carry on the data transmission. Hence, its power
consumption obviously is lower than the existing wireless
technology, and its transmission speed may reach as high as
100 Mbps, even 500 Mbps.
Chung-Cheng Chang
Department of Electrical
Engineering, National
Taiwan Ocean University
Keelung, Taiwan.
ccchang@mail.ntou.edu.tw
In broadband LNA design, resistive shunt-feedback
technique has been widely used because of its superior
broadband characteristics. However, this technique needs a
trade-off between noise figure and -3 dB bandwidth. Higher
gain can suppress the noise figure. However, higher gain
needs higher DC power.
Some applications demands high selectivity of amplifier
gain and output matching at different loads. The tuned gain
and output matching wideband LNA is appropriate for
variable gain applications and its overall performance
overtakes the performance of the standard wideband low
noise amplifier [2].
In this paper, we demonstrate the design of a tunable
broadband LNA with moderate gain and noise figure. This
paper shows the design and simulation results of a UWB
LNA.
II. CIRCUIT DESIGN
A.
Overview
For an amplifier to be considered broadband, it must
satisfy at least two simultaneous criteria [3]: good input
matching, and flat gain across a wide bandwidth. Broadband
input matching is difficult for common-source type
amplifiers due to the capacitive nature of the transistor input.
The matching requirement sets an upper limit on the size of
this capacitance and thus the size of the transistor. In the
proposed wideband design, as shown in Fig 1, a input bandpass filter structure is used to resonate the reactive part of
the input impedance, gain, NF, and power consumption.
B.
Tuned wideband
The output matching network can be tuned by varying
the gate voltage of M3. The junction capacitance between
This research is supported by National Science Council, Taiwan
1-4244-1474-1/07/$25.00 ©2007 IEEE.
Wan-Rone Liou
Graduate Institute of
Electrical Engineering
National Taipei University
San Shia, Taiwan.
wrliou@mail.ntpu.edu.tw
1226
gate and drain is change when a different gate bias is
applied. The gain and noise figure of LNA also are nce the
output frequency can be tuned to different frequencies,
creating a wideband frequency response. The tuning
network is shown in Fig. 2 [2].
C.
Input matching
The technique of filter design is employed for impedance
matching. The frequency tuning is achieved by the RLC
tank as shown in Fig. 3. The circuit achieves the wideband
input matching by a band-pass filter configuration [4]. Thus
we could derive the impedance as below. One design
method for wideband input matching involves simultaneous
impedance matching at two frequency. In Fig. 4. shows S11
against frequency [5].
D.
Figure 1. Shematic of the UWB tunable LNA
Amplifier design
The circuit uses a cascode topology to provide good
isolation between the input and output. The concept of
classical noise matching (CNM)[6] technique, and
simultaneous noise and input matching (SNIM)[7]
technique show in Fig 5. The load is designed to achieve flat
gain over the whole bandwidth. The L4 =1.99nH of the
band to improve the gain at low frequency . Resistor Rf is a
shunt-feedback resistor added to the conventional cascade
narrowband LNA. The capacitor Cf is for ac signal
coupling purpose.
Z in ( jω ) = (
≅[
1
jωL
+ j ωC +
1 −1
)
R
1
1
+ j (ω 0 + ∆ω )C + ] −1
j (ω 0 + ∆ω )
R
Figure 2. LNA tuning network
(1)
R
1
≅(
)≅
1 + 2 j∆ωRC
2 j∆ωC
E.
Noise analysis
On the other hand, the device size must yields to
sufficient noise performance and power constraint [8]. The
noise performance of the proposed topology is determined
by two main contributors: losses of the input network and
the noise of the amplifying device M 1 . The noise
contribution of the input network is due to the limited
quality factor Q of the integrated inductors [4]. The LNA
NF described by (5) depends on three of the following three
quantities: the bias current I O , the transistor width W, and
the limited quality factor of the inductors.
Figure 3. The frequency tuning RLC tank
F.
Output matching
Ω
The output matching needs to provide a 50
match.
The C4 capacitance change input and output matching.
The C5 influence whole characteristic , and the L3
adjusts S11 and S22 matching. The M3 provides the
different voltage by gate to change the performance.
1227
Ru =
γ
α 2 gd0
F (ω ) ≈ 1 +
⋅
p 2α 2 χ 2 (1− | c | 2 )
1 + 2 | c | pαχ + p 2α 2 χ 2
Ru
P(ω ) γ
+ G n Rs = 1 +
⋅
Rs
g m Rs α
(4)
(5)
Figure 8. NF, S11, S21, and S22 simulation result of the LNA
Figure 4. Input matching against frequency
Figure 5. Schematic of a cascode LNA topology adopted to apply the
CNM and SNIM techniqe.
Figure 9.
The tuning voltage relative to the S21 and NF at 5~6 GHz
Figure 6. S11, S22, S21 and NF simulation result of the tunable LNA.
Figure 10. The tuning voltage relative to the S11 and S22 at 5~6 GHz
III.
Figure 7.
P1dB
and Simulation result of two-tone test at 5 GHz
SIMULATION RESULTS
The UWB LNA was design using TSMC 0.18um CMOS
technology with a 1.5 supply voltage. The S-parameters, NF,
stability factor and linearity are simulated by the ADS
software. The input and output matching simulation results
are show in Fig. 6. The S11and S22 of LNA achieve less
than -8.7 dB throughout the frequency range of interest.
1228
As shown in Fig . 7, the cascode feedback LNA achieve s
a maximum power gain of 13.68 dB. The LNA gain
decreases when control voltage increases. The gain tuning
range are 3 and 5.5 dB at 3.9 and 7.1 GHz, respectively. The
noise figure is between 2.96~3.34dB. The noise figure
increases as the control voltage increases. The simulated
P1dB is -5.3 , and IIP3 is 15 dBm which is shown in Fig 8.
Fig. 9 shows the simulated LAN characteristics without the
tuning transistor. The tuning voltage relative to the SFig. 11. Table I
parameter and NF are shown in Fig. 10
summarizes the performance of the LNA along with results
from recently published papers.
maximum gain of 13.68 dB and a dc power consumption of
22.8 mW.
ACKNOWLEDGMENT
The authors with to thank the Chip Implementation
Center (CIC) of the National Science Council, Taiwan, ROC,
for supporting the TSMC CMOS process.
、
IV. LAYOUT
The layout of the proposed UWB LNA is presented in Fig.
12. The die area including the pads is 1.35mm by 1.35mm.
Figure 11. Silicon Layout of the LNA
TABLE I.
PERFORMANCE COMPARISON
This work
Technology
Frequency (GHz)
S11 (dB)
S21 (dB)
3.9~7.1
< -8.7
9.5
NF (dB)
P1dB (dBm)
Power (mW)
< 3.35
< -5.3
22.8
V.
[9]
[10]
0.18 um CMOS
3~5
2~10
-8.1
> -12
18
14.5~1
7.5
5.2
1.9~4
N/A
N/A
26.2
25.2
[11]
3~6
< -10
24
< 2.9
N/A
51
CONCLUSION
A tunable UWB LNA is designed in a standard 0.18um
CMOS process. The design is based on the use of resistive
feedback loops to achieve broadband gain together with low
noise and good input impedance match. The LNA can
satisfy the uniform performance specifications over a large
frequency bandwidth. A 5.5 dB gain tuning range is
achieved with this broadband LNA. It causes only 0.3 dB
increase of noise figure. In addition , the LNA has a
REFERENCES
[1] Y. Wang, J. S. Duster, and K.T. Kornegay, “Design of
an ultra-wideband low noise amplifier in 0.13 /spl mu/m
CMOS,” Circuits and Systems, 2005. ISCAS 2005.
IEEE International Symposium Vol. 5 pp:5067 – 5070 ,
23-26 May 2005
[2] M. Benmansour, , and P. R. Mukund, , “A tuned
wideband LNA in 0.25 /spl mu/m IBM process for RF
communication applications,” VLSI Design, 2004.
Proceedings. 17th International Conference pp:631 –
634, 2004
[3] D. M. Pozar, Microwave Engineering, 3rd ed. New York:
Wiley, 2003
[4] A. Bevilacqua, and A.M. Niknejad, “An ultra-wideband
CMOS LNA for 3.1 to 10.6 GHz wireless receivers,”
Solid-State Circuits Conference, 2004. Digest of
Technical Papers. ISSCC. 2004 IEEE International
Vol.1 pp:382 – 533, 15-19 Feb. 2004
[5] J.S. Paek, B. Park, and S. Hong, “CMOS LNA with
darlington-pair for UWB systems,” Electronics Letters
3rd Volume 42 pp:913 – 914, August , 2006
[6] H. A. Haus et al.,”Representation of noise in linear two
ports,” Proc. IRE, vol. 48, pp.69-74, Jan. 2002.
[7] S. P. Voinigescu et al., “A scalable high-frequency noise
model for bipolar transistors with application optimal
transistor sizing for low-noise amplifier design,” IEEE J.
Solid-State Circuit, vol. 32, pp. 1430-1439, Sept. 1997.
[8] T. H. Lee, The Design of CMOS Radio-Frequency
Integrated Circuits, second Ed., Cambridge University
Press 2004.
[9] C. Garuda ;C. Xian ; P.C. Lin; J. D. Seok; P. Zhang; M.
Ismail; “A 3-5 GHz fully differential CMOS LNA with
dual-gain mode for wireless UWB applications,”
Circuits and Systems, 2005. 48th Midwest Symposium
Vol. 1 pp:790 – 793, on 7-10 Aug. 2005
[10] C.-W. Kim, M.S. Jung, and S.G. Lee, ” Ultrawideband CMOS low noise amplifier,” Electronics
Letters Volume 41, Issue 7, pp:384 – 385, 31 March
2005
[11] D. Maxwell, S. Jung, H. Doh, J. Gao, and Y. Joo, “A
two-stage cascode CMOS LNA for UWB wireless
systems,” Circuits and Systems, 2005. 48th Midwest
Symposium on Vol. 1 pp:627 – 630, 7-10 Aug. 2005
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