ON THE DESIGN OF WIDEBAND CMOS LOW-NOISE AMPLIFIERS Reza Molavi

101 Pages·2009·5.42 MB·English

ON THE DESIGN OF WIDEBAND CMOS LOW-NOISE AMPLIFIERS
by
Reza Molavi
B.A.Sc, Sharif University of Technology, 2003
A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF
THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF APPLIED SCIENCE
in
The Faculty of Graduate Studies
^Electrical and Computer Engineering
THE UNIVERSITY OF BRITISH COLUMBIA
September 2005
©Reza Molavi, 2005
ABSTRACT
Integrated wideband low-noise amplifiers (LNAs) are used in communication applications in
which either the signal bandwidth is large or multiple narrowband signals are processed
simultaneously. An example of the former case is the recently popular ultra wideband (UWB)
wireless technology that can be used for high-data-rate low-power short-range wireless
communications. A multi-mode multi-standard wireless system is an example of the latter case.
Providing large enough gain while introducing as little noise as possible over a wide frequency
band is a challenging design task, in particular if the LNA is designed in CMOS. In this work, a
methodology for designing wideband CMOS LNAs is presented. The core of the design is the
inductively degenerated LNA which is a popular architecture in narrow-band applications due to
its superior noise and input matching properties as well as low power consumption. Wideband
performance of inductively degenerated LNA is explored both at the circuit and system level.
Trade-offs among different design requirements and their impacts on circuit parameters is
discussed in detail.
To demonstrate the effectiveness of the design technique, two wideband LNAs are designed and
simulated in a 0.18pm CMOS technology. The first LNA is intended for a multi-standard system
with the frequency range of 1.4 to 2.5GHz. The frequency band of the second LNA is from 3 to
5GHz which covers the lower band of UWB technology.
ii
TABLE OF CONTENTS
Abstract ii
Table of Contents iii
List of Tables iv
List of Figures v
Acronyms vii
Acknowledgements viii
Chapter 1 INTRODUCTION 1
1.1 Motivation 1
1.2 Research Goals 5
1.3 Thesis Outline 5
Chapter 2 BACKGROUND 7
2.1 Noise 8
2.2 Nonlinear Effects 16
• 2.3 Input Matching 20
2.4 S Parameters 24
2.5 Wideband LNA Topologies 26
Chapter 3 WIDEBAND LNA METHODOLOGY 38
3.1 Power gain and Impedance mismatch factor 39
3.2 Wideband noise and input matching 44
3.3 SNR-based Optimization Technique 52
3.4 Proposed Design Technique 58
3.5 Wideband Impedance Matching Networks 64
Chapter 4 SIMULATION RESULTS AND LAYOUT ISSUES 70
4.1 Wideband LNA for multi-standard application in 1.5-2.5GHz 70
4.2 Wideband LNA for UWB application (3.2-5GHz) 74
Chapter 5 CONCLUSIONS AND FUTURE WORK 80
5.1 Conclusions 80
5.2 Future Work 81
References 82
Appendix A Linear two port noise analysis 86
Appendix B Classic MOS device noise analysis 90
iii
LIST OF TABLES
Table 1 Wireless standards characteristics 3
Table 2 Summary of Performance 75
iv
LIST OF FIGURES
Figure 1.1 Block diagram of a simplified RF receiver 2
Figure 2.1 Thermal noise of a resistor 10
Figure 2.2 (a) Dominant sources of noise in a MOS - (b) Thevenin equivalent circuit ..12
Figure 2.3 Two-port network model of MOS device for noise calculations 14
Figure 2.4 NF calculations for a cascaded system 15
Figure 2.5 ldB compression point 17
Figure 2.6 (a) Signal spectrum of a nonlinear system (b) Graphical interpretation of IIP3
18
Figure 2.7 Different input matching topologies (a) resistive termination 21
Figure 2.8 Small signal model of an inductively degenerated LNA 23
Figure 2.9 S parameters definition of two-port networks 25
Figure 2.10 Two port model of a hunt-series amplifier 28
Figure 2.11 Common drain feedback LNA 29
Figure 2.12 Two-stage LNA for UWB applications 30
Figure 2.13 Two stage wideband LNA for UWB applications 31
Figure 2.14 Simplified block diagram of a shunt-feedback LNA 32
Figure 2.15 Schematic of thermal noise cancelling technique „ 33
Figure 2.16 Block diagram of balanced amplifier 35
Figure 2.17 Schematic of a basic distributed amplifier 36
Figure 3.1 Conceptual diagram of power transfer in an amplifier 39
Figure 3.2 Input mismatch factor with matching network 40
Figure 3.3 (a) Narrowband LNA (b) Wideband LNA 41
Figure 3.4 block diagram of a unilateral amplifier with port matching 43
Figure 3.5 Small signal model of an inductively degenerated LNA 44
Figure 3.6 Gain of LNA vs. Re{Z } and Re{Z } for UWB applications in 3-5GHz....49
in opt
Figure 3.7 NF of LNA vs. Re{Z } and Re{Z } for UWB applications in 3-5GHz 49
in opt
Figure 3.8 Gain of LNA vs. Re{Z ,j (co) for several values of Re{Z } (L) 50
op in s
Figure 3.9 NF of LNA vs. Re{Z j (co) for several values ofRe{Z J (L) 50
opt in s
Figure 3.10 Graphs of Re{Z;} and Re{Z } vs. frequency for UWB applications in 3-5GHz
n opt
(W=75um) 51
Figure 3.12 SNR<,, vs. Re{Z } and Re{Z } for UWB applications in 3-5GHz 55
U in opt
Figure 3.13 SNR of LNA vs. Re{Z ,} (co) for several values of Re{Z } (L) 56
op in s
Figure 3.14 Optimum value of Re{Zj} (L) for variations of NF 57
n s eq
Figure 3.15 Contour plots of total power consumption 60
Figure 3.16 Transit frequency (ft) vs. overdrive voltage 61
Figure 3.17 Contour plots of equivalent noise resistance (R„) 62
Figure 3.18 (a) n matching network (b) T matching network 65
Figure 3.19 Contours of constant Q„ displayed in the smith chart 66
Figure 3.20 (a) n matching network (b) Equivalent circuit 67
Figure 3.21 Real parts of impedances Z,„ and Z over the UWB band 68
eq
Figure 3.22 Imaginary parts (equivalent inductance) of impedances Z,„ and Z over the UWB
eq
band 69
Figure 4.1 Complete schematic of the multi-standard LNA 71
v
Figure 4.2 Real part matching of R and R for multi-standard LNA 72
in opt
Figure 4.3 Simulated S-parameters of the multi-standard LNA 73
Figure 4.4 Simulated NF and NF of the multi-standard LNA 73
min
Figure 4.5 Complete schematic of the UWB LNA 74
Figure 4.6 Layout of cascade amplifier for the UWB LNA 76
Figure 4.7 Nine-element equivalent model of spiral inductors 77
Figure 4.8 Simulated S-parameters of the UWB LNA (post-layout) 78
Figure 4.9 Simulated NF of the UWB LNA (post-layout) 79
Figure A.l (a) block diagram of noisy two-port network (b) Equivalent network with
input and output noise current sources 86
Figure A.2 Input Referred equivalent noise model 87
Figure B.l (a) Noise sources of a MOS device b) Equivalent input referred model 90
vi
ACRONYMS
ADC Analog to Digital Converter
ADS Advanced Design Systems
CAD Computer Aided Design
CMOS Complementary Metal Oxide Semiconductor
CNM Classical Noise Matching
DA Distributed Amplifier
DAC Digital to Analog Converter
DSM Deep Sub Micron
DSP Digital Signal Processing
GPS Global Positioning System
GSM Global System for Mobile Communication
IMF Impedance Mismatch Factor
IMP Inter Modulation Product
KCL Kirchhoff Current Law
KVL Kirchhoff Voltage Law
LNA Low Noise Amplifier
LO Local Oscillator
MCM Multi Chip Module
MIM Metal Insulator Metal
NF Noise Figure
PCNO Power Constrained Noise Optimization
PCSNIM Power Constrained Simultaneous Noise and Input Matching
PCWSNIM Power Constrained Wideband Simultaneous Noise and Input Matching
RF Radio Frequency
SiP System in Package
SNIM Simultaneous Noise and Input Matching
SNR Signal to Noise Ratio
UMTS Universal Mobile Telecommunication System
UWB Ultra Wide band
VCO Voltage Controlled Oscillator
yswR Voltage Standing Wave Ratio
WLAN Wireless Local Area Network
WPAN Wireless Personal Area Network
vii
ACKNOWLEDGEMENT
There are many friends and colleagues that I would like to thank for their invaluable help and
support during my years at UBC. First of all, I would like to thank my supervisor and friend, Dr.
Shahriar Mirabbasi who gave me the opportunity to join his research group at UBC. His keen
knowledge on the design of analog/RF integrated circuits was the key factor in the success of this
research project. I am particularly grateful for the great advises, both technical and personal, that
he gave me over these years. Also, I would like to thank Dr. Ivanov and Dr. Schober for reading
my thesis and serving as my committee members.
I am honoured to call myself part of SoC research group. Working with a group of
brilliant researchers who were, undoubted fully, great motives throughout my research years, was
a great privilege I benefited in SoC lab. I would like to express appreciations to all my friends at
SoC particularly to Scott Chin, Howard Yang, Amit Kedia, Karim Allidina, Neda Nouri, Melody
Chang, Samad Sheikhai, Pedram Sameni, Dipanjan Sengupta, Peter Hallschmid, Marwa
Hamour,Behnoosh Rahmatian, Xiongfei Meng and Shirley Au. I also thank Roberto Rosales,
Roozbeh Mehrabadi and Sandy Scott for their help and support in the SoC lab. I would like to
extend my gratitude to all my friends and relatives in Canada and US with whom I shared great
memories in the past two years, especially my uncles in Seattle, Farbod Abtin, Amirhossein
Heydari, Amir Sadaghianizadeh and Ali Mashinchi.
The last but the most, I would like to express my deepest appreciation to my wonderful
parents and brother for their continuous love, inspiration and support. I could feel their
supportive presence in every single moment of these two years even though they were physically
miles away from me. Thank you from the bottom of my heart!
This research was supported by NSERC and SiRF Technology Inc.
viii
This thesis is dedicated to:
My father who is and will always be my best friend and teacher,
My mother without whose unconditional support I would not be where I am today,
My brother who is and will always be my most trustworthy friend,
and
My beautiful country, Iran.
ix
Chapter 1 - Introduction 1
CHAPTER 1
INTRODUCTION
1.1 Motivation
Communication technology is moving toward a major milestone. The explosive growth of the
wireless industry, global access to the internet, and the ever increasing demand for high speed
data communication are spurring us toward rapid developments in communication technology.
Wireless communication plays an essential role in this transformation to the next generation of
communication systems. Cellular phones, pagers, wireless local area networks (WLAN), global
positioning system (GPS) handhelds, and short-range data communication devices employing
Bluetooth and ultra wideband (UWB) technologies are all examples of portable wireless
communication devices. Nowadays, driven by the insatiable commercial demand for low-cost
and low-power multi-standard portable devices, RT designers are urged to develop new
methodologies that allow the design of such products.
An irreplaceable component of any RF receiver is the front-end low-noise amplifier
(LNA). As the first active building block in the receiver front-end, the LNA should provide
considerable gain while minimizing the noise introduced to the system. Fig. 1.1 depicts the
simplified structure of an RF receiver. The received signal is typically filtered, amplified by an
LNA and translated to the base-band by mixing with a local-oscillator (LO). After being
demodulated, the signal is applied to an analog-to-digital converter (ADC) which digitizes the
analog signal. The digital signal is then processed in a digital signal processing unit (DSP). As