A novel cmos model design for 2 6 g hz wideband lna input matching using resistive feedback topology

1. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
INTERNATIONAL JOURNAL OF ELECTRONICS AND
17 – 19, July 2014, Mysore, Karnataka, India
COMMUNICATION ENGINEERING & TECHNOLOGY (IJECET)
ISSN 0976 – 6464(Print)
ISSN 0976 – 6472(Online)
Volume 5, Issue 8, August (2014), pp. 55-60
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IJECET
© I A E M E
A NOVEL CMOS MODEL DESIGN FOR 2-6 GHz WIDEBAND LNA INPUT
MATCHING USING RESISTIVE FEEDBACK TOPOLOGY FOR WIMAX
APPLICATIONS
M.Ramanareddy1, N.S.Murthy sarma2, P.Chandrasekhar3
1Asst.Professor, dept of ECE, CBIT, HYD, IND
2Professor, Dept of ECE, BVC, A.P,E., IND
3Assoc.Professor, Dept of ECE, OU, HYD, IND
55
ABSTRACT
The proposed LNA designed structure is a fully integrated 2-6 GHz two stage resistive shunt
feedback with simplified band pass circuit provide wide input impedance matching. In addition the
amplifier adapts the cascode structure .The high gain, low noise, low power CMOS LNA is designed
for an WIMAX applications with TSMC 0.18μm RF CMOS process. The maximum gain (S21) is
16.5dB, minimum noise figure is 4.2 dB, the input return loss is -12dB over 2-6 GHz range. The bias
currents are 8.54ma, 4.15ma for first and second stage circuit by a overall power consumption is
15mw.
Keywords: RF CMOS, VLSI Design, Wireless Communications, Low Noise Amplifier, Cascode,
Input Return Loss, Wimax.
1. INTRODUCTION
Since last decade several CMOS LNA’S have been reported at 802,11/6,802.11/a and GSM
standard, although the WiMAX is a new wireless wideband technology specified by IEEE 802.16e
standards. The network structures developed for existing internet is insufficient, such that so many
developers are try to improve this problem. The best solution for low cost, for high integration
processing and analog circuits to be mixed with digital one is CMOS technology.

2. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM
17 – 19, July 2014, Mysore, Karnataka, India
Fig 1: RF Front end circuit
From fig(1),the low noise amplifier is one of the most crucial blocks in a receiver sec
communication systems. Because of the sensitivity is mainly determined by the LNA performance
with respect to mainly noise figure and gain.
input impedance matching.
The WiMAX provide 75mbps data r
area network access scheme and also cope with NLOS(none line of sight) and LOS(line of sight.
sight)transmission conditions. It can also expanded 3G,
Basic LNA requirements:
1. Gain (10-20 db) to amplify the received signal and to reduce the input referred noise of the
subsequent stages.
2. Good linearity: Handling large undesired signals without much distortion.
3. Low noise for high sensitivity
4. Maximum power gain 50 W termination for proper operation and can route the LNA to the
antenna which is located an unknown distance away without worrying about the length of the
transmission line [7].
1.1 Basic Topologies
1. Wide band LNA input matching topologies (a) Resistive te
(c) resistive shunt feedback.
2. Narrow band LNA input matching topologies (a) inductive degenerated (b) resistive terminated
[7]
2. LNA CIRCUIT DESIGNING
1.1 LNA Design requirements
In Modern Electronic or optical Communication systems the Broadband amplifiers are
Widely used because they can have perfect technical matching impedance, good linearity better
better noise performance. For Low to high frequencies.
matching stage, gain stage amplifiers are two feedback network and output matching stage.
56
ecause LNA is first stage of receiver such that it provide better
rate with coverage area 50km range by a metropolitan
Cable modem, wired broad band access.[
termination (b) common gate
The proposed LNA c
-2014
ly section of
ate 8].
rmination gain,
consists of input

3. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
RFin
Input
matching
Stage
Feedback
Network
stage
Two
gain
Amplifie
r
atching
Stage
output
m
R
Fig 2: Block diagram for a fully integrated 2-6 GHz low noise
In order to achieve a perfect high gain, broad band, we use cascode amplifier with RC
feedback. In the design of Cascade Configuration, the Common-Source stage is the critical stage for
good linearity, better noise figure and high performance because LNA affected by the gate width
(M1&M2) Vgs of CS transistor.
Fig.3: The proposed LNA with cascode and RC feedback networks
The cascode configurations can control the gate to drain capacitance cgd of M1 transistor(it is
direct paths between in and at the cgd can limit the high frequency response of the amplifier[5] By
satisfaction of gain, input/output return loss and ability, then any noise figure of feedback amplifier
optimizations is possible[1]. The feedback resistance value is varied the parameters noise figure
minimum, maximum gain (gmax) and parameter S11, S22 of the feedback amplifier is changed as
shown is table below.
Table(1): Effect on feedback resistance
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Feedback
Resistance
Gmax NFmin Input/output
Return loss(max)
500 10.5 3.6 -14.2 -14.6
600 11.1 3.5 -12.7 -12.6
700 11.6 3.4 -11.5 -10.8
800 12 3.3 10.7 -9.6

4. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
c2 L2
RFin RFout
L1
Fig 4: Input network passive components
Fig.4 A simple passive elements or strip lines are used to match the input or output
impedances of narrowband LNA’s. In wideband or broad band, impedance matching is complicated.
The simplified band pass filter [6] is shown in below figure for perfect impedance matching in
proposed design.
Fig 5: The proposed wideband low noise amplifier
Fig.5 Can represent the proposed CMOS broadband LNA. With cascade technique. The
simplified band pass filter is used such that to reduce the q factor, Perfect impedance matching and to
achieve wideband[6] the inductors’ L3 and L4, Cs and Ls can improve the increase the gain, flatness
of the gain.
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3. SIMULATED RESULTS AND ANALYSIS
The Simulated and measured results of a broad band. CMOS LNA operating at the frequency
range from 2 to 6Ghz. It was implemented. In 0.18um RF CMOS technology process. From design
flow step, circuit simulated, layout of a circuit have been determined frequencies Fig 6(a) to 6(e)
shows (input return loss, output return loss S22, power gain S21, reverse isolation S12). The power
gain 16.8dB and S12 is below -32 dB within the bandwidth The fig 10 shows the noise figure (NFs).
The power consumption fig 11 shows the 145 mw.

5. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
Fig 6(a) Fig 6(b)
Fig 6(c) Fig 6(d)
Fig 6(e)
Fig.6: (a) S11 parameters (b)S12 Parameters (c) S21 parameters.
(d) S22 parameters (e) Noise figure
59

6. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
Ref. Tech S21(dB) S11(dB) S22(dB) NF(dB) B.W(GHz)
[5] CMOS 0.18μm 9.3 -9.9 - 4 2.4-9.5
[6] CMOS 0.18μm 9.8 -9 - 2 2-5
[7] CMOS 0.18μm 14 -9.9 -10 2 3-5
p.work CMOS 0.18μm 16.4 -10 -8.5 4 2-6
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CONCLUSIONS
The designed wideband LNA is used for WiMAX applications for frequency range from 2 to
6 GHz. The band pass filter with resistive feedback technique provide perfect input matching. The
gain stage amplifier with cascade structure provide better flat gain response. The designed LNA
provides 16.5 dB and minimum noise figure of 4 dB at 3.5Ghz. The bias current is 8.54mA at
second stage circuit 4.15mA by a 1.1 and power Consumption is 14.5mw. The summarized
performance of proposed LNA design with existing designed LNA is which is used in wide band
applications. The below table represents the performance comparison table from different analysis
Table 2: Performance comparison table
REFERENCES
Journal papers
[1] Yang Lu: Kiat Seng Yeo: Cabuk, A: Jianguo Ma: Jianguo Ma: Manh Anh Do: Zhengho Lu,
“A Novel CMOS LNA Design for 3.1-1.6 GHz Ultra –wide band Wireless Receivers”, IEEE
JNL, VOL 53, PP.1683-1692, Aug 2006.
[2] A Bevilacqua and A.M Niknejad, “An Ultra wideband CMOS low noise amplifier for
3.1-10.6GHz wireless receivers”, IEEE Journal of solid state circuits, vol.39, no.12.
pp.2259-2268, dec 2004
[3] C.W Kim, M,-S Kang,”An Ultra –wideband CMOS Low noise amplifier for 3.5GHz UWB
system” IEEE Journal of solid –state Circuits, Vol.40, No 2, Feb-2005.
Theses
[4] ECEN 665 (ESS) “RF Communication Circuits and Systems”.
Proceedings Papers
[5] Garuda,C:xian Cui:Po-Chin Lin:Seok joo Doo: Pengbei Zhang: Ismail,M.’a 3-5. GHz Fully
Differencial CMOS LNA with dual–gain mode for wireless UWB applications” Mwscas.
2005, Vol.1, pp.790-793, Aug.2005.
[6] Ben Amor, M.:Loulou, M:Quintanel, S.: Pasquet,D.:”A Wideband CMOS LNA Design for
WiMAX applications”, ECCSC 2008, PP.93-96, july 2008.
Websites
[7] Agilent Technologies, Web.http://prphotos.tm.agilent.com/2010/03sepem101109/index.html.
[8] WiMAX Forum, http://www.WI MAXforum.org, 2006.