Temperature analysis of lna with improved linearity for rf receiver

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 03 Issue: 03 | Mar-2014, Available @ http://www.ijret.org 407
TEMPERATURE ANALYSIS OF LNA WITH IMPROVED LINEARITY
FOR RF RECEIVER
Suvarna Gulab Shimpi1
, Subha Subramaniam2
, Vidya Gogate3
1
Shah and Anchor Kutchhi Engineering College, M.E. Electronics, Mumbai University, Maharashtra, India
2
Shah and Anchor Kutchhi Engineering College, Department of Electronics, Mumbai University, Maharashtra, India
3
Shah and Anchor Kutchhi Engineering College, Department of Electronics, Mumbai University, Maharashtra, India
Abstract
In this paper we are fully integrated 5.5 GHz high-linearity low noise amplifier (LNA) is designing using post-linearization technique,
in sub-120nm & sub-70nm technology. It developed using cascode amplifier with inductors. RC linearization circuit is designed to
improve the linearity of the design. Cascode LNA circuit is designed for linearity improvement. In this work Temperature analysis is
carried out for LNA circuit performance improvement fully integrated 5.5 GHz high-linearity low noise amplifier (LNA) is designing
using post-linearization technique, in sub-120nm & sub-70nm technology.
Temperature stability of the circuit is analysed for different temperature ranges our results prove that the proposed LNA design
achieve high gain with good linearity. Although power dissipation of the circuit is high, good temperature stability is achieved.
Temperature stability of the circuit is analysed for different temperature ranges our results prove that the proposed LNA design
achieve high gain with good linearity. Although power dissipation of the circuit is high, we are able to achieve good temperature
stability. The Low Noise Amplifier is a special type of electronic amplifier used in communication systems which amplifies very weak
signals captured by an antenna.
Keywords: Linearity improvement LNA circuit, DSCH and Microwind software.
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1. INTRODUCTION
Recently, telecommunication systems require high
performance, low noise, low power, and highly linear RF
integrated circuits [1]
. Since the digital modulation scheme
requires highly linear RF front-end circuits, the linearity
requirement of the LNA becomes more stringent. Owing to
possible large interference signal tones at the receiver end
along with the carrier, the LNA is expected to provide high
linearity, thus preventing the intermodulation tones created by
the interference signal from corrupting the carrier signal.
Moreover, the high linearity should be achieved in
combination with a high gain and low current consumption.
However, its poor linearity limits its usage to high-jammer
applications.
To improve the linearity of the cascode LNA, several
linearization methods have been proposed. Multiple gated
transistors (MGTR) techniques is introduced by Kim, T. W.,
B. Kim, and K. Lee [2], which falls under the category of feed
forward, uses two transistors connected in parallel and biased
in weak and strong inversion region, respectively. The folded
cascode PMOS topology has been proposed by Kim, T. S. and
B. S. Kim [3]. Moreover, this topology has the advantages of
low transconductance and low current consumption. Another
linearization method, post-linearization technique, is
introduced by Zang, H., X. Fan, and E. S. Sinencio [4]. This
linearization technique uses a diode connected NMOS
transistor to apply to a cascode common gate (CG) LNA, and
the linearity performance looks good. However, by applying
this technique to a cascode CS LNA, the linearity
improvement is needed at the penalty of degrading the gain
and current consumption.
In a common source (CS) circuit, the cascode topology is
often employed to provide high gain and high reverse
isolation. cascode stage Gain can be increased by increasing
the length of the input transistor for a given bias current. Note
that the transconductance of M1 becomes half and leading to
higher noise. The application of cascode topology is in
building constant current sources Published by Behzad Razavi
[12].
In this paper, we present a post-linearization technique for the
cascode CS LNA with the comparison of sub-70nm and sub-
120nm technology. In the proposed method, sub-70nm
technology circuit Gain and power dissipation is almost
constant for variations of temperature, which is suitable for the
high-frequency and high-linearity cascode CS LNAs.

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2. DETAIL OF CMOS LNA
The schematic diagram of the proposed LNA is shown in Fig.
1. The idea behind the cascode structure is to convert the input
voltage to a current and apply the result to a common gate
stage. Transistor in a common source arrangement converts a
voltage signal to a current signal. The cascade of a CS stage
and a CG stage is called a “cascode” topology. The basic
configuration: M1 generates a small signal drain current
proportional to Vin and M2 simply routes the current to RD.
M1 is the input device and M2 is the cascode device. An
important property of the cascode structure is its high output
impedance. Voltage gain of the cascode stage is equal to that
of common source stage.
The inductive source degeneration structure provides
simultaneous input matching. At higher frequencies, the
device capacitances, such as gate-to-source, gate-to-drain,
drain-to-substrate and source-to-substrate capacitances,
significantly affected the current-voltage relationship. The
input impedance seen from RFin of LNA is the same with and
without the linearization circuit (L.C.) refered from [4]. The
degradation in gain and current consumption is not severe
because the transconductance and bias current of the
linearization circuit are much smaller than those of the
cascode stage.
An important property of the cascode structure is its high
output impedance [12]. The circuit can be viewed as a
common source stage with a degeneration inductor. M2 boosts
the output impedance of M1. Cascoding can be extended to
three or more stacked devices to achieve higher output
impedance. It is also interesting to compare the increase in
gain due to cascoding with that due to increasing the length of
the input transistor for a given bias current. Transistor Ma,
Resistor R1 and Capacitor C1 this components are use for
linearization. For example, that the length of the input
transistor of CS stage is quadrupled while the width remains
constant.
Fig 1 Schematic diagram of the proposed LNA [11]
3. EXPERIMENTAL RESULTS AND DISCUSSION
The LNA under this study was fabricated with a standard sub-
120nm & sub-70nm CMOS technology on a p-type substrate.
The proposed LNAs consume only 10mW (sub-120nm tech)
& 6.58mW (sub-70nm tech) DC power supply voltage of 1V.
For comparison, the LNAs with different temperature are
realized.
Table1 Performance comparison with sub-70nm & sub-
120nm Technology of LNA with Temperature
The measured gain, Power dissipation, and output voltage of
the LNAs are plotted in the following Figures.
The gains are approximately 9.7 dB and 13.7 dB, respectively,
sub-120nm & sub-70nm Technology at 5.5 GHz. The power
dissipation of the LNAs are approximately and 23.37 uW &
31.67 uW, respectively, sub-120nm & sub-70nm Technology
at 5.5 GHz.
Here we are comparing the gain of the LNA circuit with two
different technologies with temperature
Table 2 – Analysis of AV in terms of temperature and
frequency for different biasing voltages (sub-120 nm
technology)
Sub-120nm tech Sub-70nm tech
Temp
in °C
Gain
in dB
power
dissipation
in uW
gain
in dB
power
dissipation
in uW
15 10.7 22.16 14.1 31.56
20 10.2 22.77 13.9 31.59
25 9.7 23.37 13.7 31.67
30 9.1 23.95 13.5 31.8
35 8.5 24.52 13.4 31.97
40 7.8 25.4 13.2 32.2
Biasin
g
voltag
e in
volts
Vb1= 0.5V, Vb2 =
1.05V
Vb1= 0.5V, Vb2 = 1V
Temp
in °C
Gai
n in
dB
power
dissipat
ion
(uW)
Vout
(Volt)
Gai
n in
dB
power
dissipatio
n (uW)
Vout
(Volt)
15°C 10.7 22.16 0.343 11.9 54.077 0.397
20°C 10.2 22.77 0.324 11.8 54.247 0.394
25°C 9.7 23.37 0.305 11.6 54.414 0.382
30°C 9.1 23.95 0.286 11.5 54.76 0.381
35°C 8.5 24.52 0.267 11.2 55.85 0.367
40°C 7.8 25.4 0.246 11.1 55.97 0.366

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By keeping biasing voltage Vb1 constant and a small change
in biasing voltage Vb2. By keeping Resistor of RVb2 constant
and reduce the Resistor of RVb1, power dissipation of the
circuit can be change.
It means that, Voltage gain of the circuit changes by varying
biasing voltages, as biasing voltage varies it changes current
Idd also. As we change the value of biasing resistors it affects
the power dissipation of the circuit. Small change in biasing
voltage changes the Voltage gain.
Table 3 - Analysis of AV in terms of temperature and
frequency for different biasing voltages (sub-70nm
technology)
For Table – 3 By keeping biasing voltage Vb1 constant and a
small change in biasing voltage Vb2, gives use large change in
Voltage gain.
Table 4 Comparison of Vout performance of the (sub-70nm &
120nm tech) LNA with temp
Fig 2 Compared Vout performance of the (sub-70nm & sub-
120nm tech) LNA with temp.
From table4, as temperature increases output voltage
decreases. It means the performance of the output voltage is
dependent on the temperature. The output voltage of the sub-
70nm technology is higher than the sub-120nm technology.
This compared with the graph as shown in figure 2.
It is also interesting to compare the increase in gain due to
cascading with that due to increasing the length of the input
transistor for a given bias current. The length of the input
transistor of a CS stage is quadrupled while the width remains
constant. The application of cascode topology is in building
constant current sources. The linearization is obtained at the
cost of lower gain and higher noise.
However, the input device and the cascode device need not be
of the same type. Instead of NMOS we can use PMOS.
The comparisons of the circuit performance with the recently
published LNAs with 25°C temperature are summarized in
Table 5.
Table 5 Performance comparisons with the recently published
LNAs
(a) sub-120nm
Vb1= 0.5V, Vb2 = 1.05V Vb1= 0.5V, Vb2 = 1V
Temp
in °C
gain
in
dB
power
dissipation
(uW)
Vout
(Volt)
gain
in
dB
power
dissipa
tion
(uW)
Vout
(Volt)
15°C 14.1 31.56 0.508 18 28.075 0.792
20°C 13.9 31.59 0.497 18 28.095 0.788
25°C 13.7 31.67 0.488 17.9 28.1 0.786
30°C 13.5 31.8 0.479 17.9 28.099 0.785
35°C 13.4 31.97 0.47 17.8 28.1 0.774
40°C 13.2 32.2 0.462 17.8 28.146 0.774
Technology 120nm 70nm
Gain in dB 9.7 13.7
Pdc in mW 10 6.58
Output voltage in Volts 0.305 0.488
PowerDissipation in uW 23.37 31.67
Temperature
in °C
Sub-70nm
tech Vout
in Volt
Sub-120nm
tech Vout in
Volt
15 0.508 0.343
20 0.497 0.324
25 0.488 0.305
30 0.479 0.286
35 0.47 0.267
40 0.462 0.246

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(b) sub-70nm
Fig 3 Voltage Gain (dB) vs Frequency (Hz) of linearity
improvement LNA circuit
From figure 3 Linearity Improvement LNA implemented and
simulated on sub-120nm tech & Sub-70nm technology. The
simulation result shows that as temperature of the circuit
increases the Voltage Gain reduces.It should be noted that the
proposed LNAs are fully integrated without off-chip
components. The proposed technique usable at higher
frequency range
Equations
Gain =
Vout
Vin
in dB (1)
4. CONCLUSIONS
From our simulation results depicts the fact that the down
scaling in VLSI technology increases gain for sub-70nm in
comparison with the same implementation in sub-120nm. We
have designed and shown a improved linearity improvement
circuit for LNA with better gain.
The design shows temperature stability with increased gain.
The limitation of this design is with the power dissipation of
the circuit.
We are proving again the well known fact that the down
scaling improves gain.
The proposed linearization technique adopts an additional
folded diode with a resistor and capacitor in parallel.
REFERENCES
[1]. Wong, S. K., F. Kung, S. Maisurah, M. N. B. Osman, and
S. J. Hui, “Design of 3 to 5 GHz CMOS low noise amplifier
for ultra-wideband (UWB) system,” Progress In
Electromagnetics Research C, Vol. 9, 25 - 34, 2009.
[2]. Kim, T. W., B. Kim, and K. Lee, “Highly linear receiver
front-end adopting MOSFET transconductance linearization
by multiple gated transistors,” IEEE J. Solid-State Circuits,
Vol. 39, 223 - 229, January 2004.
[3]. Kim, T. S. and B. S. Kim, “Post-linearization of cascode
CMOS low noise amplifier using folded PMOS IMD sinker,”
IEEE Microwave and Wireless Components Letters, Vol. 16,
182 - 184, April 2006.
[4]. Zang, H., X. Fan, and E. S. Sinencio, “A low-power,
linearized, ultra-wideband LNA design technique,” IEEE J.
Solid-State Circuits, Vol. 44, 320 - 330, February 2009.
[5] Choi, K., T. Mukherjee, and J. Paramesh, “A linearity-
enhanced wideband low-noise amplifier,” IEEE RF Integrated
Circuits Symp. Dig., 127{130, June 2010.
[6]. Chang, C. P., J. H. Chen, S. H. Hung, C. C. Su, and Y. H.
Wang, “A novel post-linearization technique for fully
integrated 5.5 GHz high-linearity LNA,” IEEE Int. Innovative
Computing, Information and Control Conf., 577{580,
Kaohsiung, Taiwan, December 2009.
[7]. Aparin, V. and L. E. Larson, “Modified derivative
superposition method for linearizing FET low-noise
amplifiers," IEEE Trans. Microw. Theory Tech., Vol. 53, 571
- 581, February 2005.
[8]. Chandrasekhar, V., C. M. Hung, Y. C. Ho, and K.
Mayaram,A packaged 2.4 GHz LNA in a 0.15 ¹m CMOS
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[9]. Youn, Y. S., J. H. Chang, K. J. Koh, Y. J. Lee, and H. K.
Yu, “A 2 GHz 16dBm IIP3 low noise amplifier in 0.25 um
CMOS technology,” IEEE Int. Solid-State Circuits Conf., 452
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[10]. Im, D., I. Nam, H. Kim, and K. Lee, “A wideband
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[11]. C.-P. Chang, W.-C. Chien, C.-C. Su, and Y.-H. Wang,”
Linearity Improvement of cascode cmos LNA using a diode
connected nmos transistor with a parallel rc circuit”, Progress
In Electromagnetics Research C, Vol. 17, 29 - 38, 2010
[12]. Behzad Razavi, “Design of Analog CMOS Integrated
Circuits”, Published by Tata McGraw-Hill Education Private
Limited, Edition 2002, 25th reprint 2013
BIOGRAPHIES
Suvarna Gulab Shimpi M.E. Electronics,
SAKEC, Mumbai University, Mumbai, India
suvilas@gmail.com
Subha Subramaniam Associate Professor,
SAKEC, Department of Electronics,
Mumbai, India
subhasubramaniam@yahoo.co.in

__________________________________________________________________________________________
Vidya Gogate, Assistant Professor, SAKEC,
Department of Electronics, Mumbai, India
vidyagogate@gmail.com

Temperature analysis of lna with improved linearity for rf receiver

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Temperature analysis of lna with improved linearity for rf receiver