Baseband Analog Circuits for Software Defined Radio

cnasic

Contents
Dedication v
Preface xi
Acknowledgments xv
1 I+ @/ v5 s0 t& X# j. S3 \9 k! A$ z: T1. 4G MOBILE TERMINALS 1
% i' K" ^% X3 R1 E1.1 A Wireless-Centric World 1
3 p" P8 Y$ F; p# u$ H+ y9 c1.2 The Driving Forces Towards 4G Systems 3
1.3 Basic Architecture For a 4G Terminal 6
' q$ `: j: ^  ?: \' F% F8 O1.4 The Role of Analog Circuits 8
1.5 Energy-Scalable Radio Front End 9
, P6 F* H4 k9 R' d1.6 Towards Cognitive Radios 11
2. SOFTWARE DEFINED RADIO FRONT ENDS 13
2.1 The Software Radio Architecture 13
5 u8 B, x( i' F2 |  K2.2 Candidate Architectures for SDR Front Ends 16
2.2.1 Heterodyne and digital-IF receivers 17
8 I6 I$ Y( K! A% G( b% M2.2.2 Zero-IF receivers 19
6 c) S) }6 T* j6 r, J8 H2.2.3 Digital low-IF receivers 22
2.2.4 Bandpass sampling receivers 24
2.2.5 Direct RF sampling receivers 26
$ X/ n1 w2 p" A2.3 SDR Front End Implementation 27
2.3.1 LNA and input matching 29
2.3.2 Frequency synthesizer 30
2.3.3 Baseband signal processing 31
4 V4 E  B, r  Q, G4 C  I  _2.3.4 Measurements results 31
" Q8 R% M9 p3 ?/ O2.4 Digital Calibration of Analog Imperfections 33
- F; ~$ X! d; ?4 M  \+ W3 Z. ]2.4.1 Quadrature imbalance 34
$ a: x8 F1 E* }' b# R, F2.4.2 DC offset 36
7 T  d0 L( {! b% R: Tviii Contents
8 g! \; A  Z/ q* \8 x& ?: D2.4.3 Impact of LPF spectral behavior 36
( Z; K* I, Q" ~2.5 Conclusions 37
3. LINK BUDGET ANALYSIS IN THE SDR ANALOG
; S* [  `, W$ ^* g1 {5 k% RBASEBAND SECTION 39
: B$ u2 X, ~+ y  O+ G3.1 Analog Baseband Signal Processing 39
, r! y0 v) S+ ^* |3.2 Baseband Trade-Offs for Analog to Digital Conversion 40
% u" I5 b* q" r3.2.1 Number of poles for the LPF 41
# c6 g' W( p  o( w2 a6 Q  h, \3.2.2 ADC dynamic range 42
) s% a5 q/ {( c( z. b. Y3.2.3 Baseband power consumption estimation 47
3 g/ N5 n. {8 i! b. l, D3.3 Multistandard Analog Baseband Specs 48
3.4 Multimode Low-Pass Filter 49
3 m. K+ K2 M0 L& s- H7 U3.4.1 Filter selectivity 50
3.4.2 Filter noise and linearity 54
( R" T6 b: K7 j8 O+ y4 q; D3.4.3 Filter flexibility planning 56
! a. ^: S4 o4 `" K4 B3.4.4 Cascade of biquadratic sections 59
* o, V0 a" p! D3 w1 u7 n, H3.5 Automatic Gain Control 62
3.6 Conclusions 65
2 {" r0 d' N# t( [3 M' W4. FLEXIBLE ANALOG BUILDING BLOCKS 67
" J2 H4 ]6 W/ k% k2 ~4.1 Challenges in Analog Design for Flexibility 67
4.2 A Modular Design Approach 68
8 B9 ~$ [* r9 n4.3 Flexible Operational Amplifiers 70
4.3.1 Variable current sources 70
4.3.2 Arrays of operational amplifiers 71
6 m- M/ A6 t: E4.4 A Digital-Controlled Current Follower 75
4.5 Flexible Passive Components 75
4.6 Flexible Transconductors 77
4.7 Flexible Biquadratic Sections 78
  g4 V/ H2 {2 T& G4.7.1 The Active-Gm-RC biquad 79
4.8 Conclusions 91
5. IMPLEMENTATIONS OF FLEXIBLE FILTERS FOR SDR
FRONT END 93
5.1 State of the Art for Flexible CT Filters 93
7 a1 B4 W+ ^) k% ~4 y5 x$ y) N" l% y5.2 A Reconfigurable UMTS/WLAN Active-Gm-RC LPF 94
! v, d+ E( i% Y1 Y5.2.1 Filter architecture 96
5.2.2 Automatic RC calibration scheme 97
: K- D" i" m. E! o5.2.3 Measurements results 102
Contents ix
$ U& f- }; v: ]; i, Q% M- [6 |5.3 LPF and VGA for SDR Front End 105
5.3.1 LPF and VGA architectures 107
5.3.2 Prototype measurements 111
9 |: P" d/ n0 P  g" @0 {, ]! f. U5.4 Conclusions 118
Acronyms 119
3 F! u  n' M! c& wList of Figures 123
List of Tables 129
References 131
1 R8 n2 E% y6 H/ x: sIndex 139