Baseband Analog Circuits for Software Defined Radio

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Contents
2 G0 r1 t0 K/ a& y) \, YDedication v
2 G* K! G4 r7 ~! g% i+ ]8 xPreface xi
Acknowledgments xv
1. 4G MOBILE TERMINALS 1
/ l5 E! F$ ]1 Z4 Y; p1.1 A Wireless-Centric World 1
! r* @1 v$ f1 h. d: z0 N& c' I* e1.2 The Driving Forces Towards 4G Systems 3
1.3 Basic Architecture For a 4G Terminal 6
4 F6 R0 ^. g* H" X5 ^1 X. g$ ~1.4 The Role of Analog Circuits 8
1.5 Energy-Scalable Radio Front End 9
* z3 b) l7 e3 a  `6 V7 H1.6 Towards Cognitive Radios 11
+ U! v9 |4 @4 E- Q) M' _: v2. SOFTWARE DEFINED RADIO FRONT ENDS 13
2.1 The Software Radio Architecture 13
- b& F/ R# \$ ]' G! Y# J3 x2.2 Candidate Architectures for SDR Front Ends 16
6 T2 A- [/ N/ R2 e' z( ~4 q2.2.1 Heterodyne and digital-IF receivers 17
2.2.2 Zero-IF receivers 19
4 H! x/ h* K5 D2.2.3 Digital low-IF receivers 22
2.2.4 Bandpass sampling receivers 24
2.2.5 Direct RF sampling receivers 26
2.3 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
2.3.4 Measurements results 31
4 Y/ @/ a" |+ F7 m& v; x* ~2.4 Digital Calibration of Analog Imperfections 33
/ b; i& ], C" t1 P  x. u/ o2 m4 P2.4.1 Quadrature imbalance 34
2.4.2 DC offset 36
viii Contents
2.4.3 Impact of LPF spectral behavior 36
% k4 _- T6 Q  b$ C  B5 d, h1 {2.5 Conclusions 37
& z+ H2 B7 \1 P) @+ j2 {7 R0 F, l3. LINK BUDGET ANALYSIS IN THE SDR ANALOG
7 c% E" s6 Y' h7 @5 G  T& yBASEBAND SECTION 39
3.1 Analog Baseband Signal Processing 39
3.2 Baseband Trade-Offs for Analog to Digital Conversion 40
/ {7 r$ k9 K) I  x3.2.1 Number of poles for the LPF 41
6 l6 ]! J7 x7 [" C$ r' E3.2.2 ADC dynamic range 42
3.2.3 Baseband power consumption estimation 47
" _' {3 W6 f+ B" N3 ?6 e$ Z3.3 Multistandard Analog Baseband Specs 48
4 k# `6 J1 q- \, T4 E3.4 Multimode Low-Pass Filter 49
& n) r2 P3 k& r( V3.4.1 Filter selectivity 50
# B' {( z3 S! u' c7 k. s3.4.2 Filter noise and linearity 54
8 Z. `+ V- {" P/ ?: G. B3.4.3 Filter flexibility planning 56
' c! e* q* T) a, q: e% w3.4.4 Cascade of biquadratic sections 59
0 x2 F6 V, S% s% R0 I* [3.5 Automatic Gain Control 62
- R5 h) i2 y8 e. d% k  ]/ p3.6 Conclusions 65
, A$ s& p2 M$ i' W5 m  E/ U4. FLEXIBLE ANALOG BUILDING BLOCKS 67
% `/ L. b# u& b$ i# K- W. ]3 c4.1 Challenges in Analog Design for Flexibility 67
4.2 A Modular Design Approach 68
8 U- R7 T3 N- a; S) [4.3 Flexible Operational Amplifiers 70
4.3.1 Variable current sources 70
4.3.2 Arrays of operational amplifiers 71
4.4 A Digital-Controlled Current Follower 75
4.5 Flexible Passive Components 75
4.6 Flexible Transconductors 77
# |+ ^! \1 h* h9 T6 G5 L4.7 Flexible Biquadratic Sections 78
4.7.1 The Active-Gm-RC biquad 79
4.8 Conclusions 91
5. IMPLEMENTATIONS OF FLEXIBLE FILTERS FOR SDR
. ?1 V4 R& d9 S" T" k# o  ?FRONT END 93
5.1 State of the Art for Flexible CT Filters 93
5.2 A Reconfigurable UMTS/WLAN Active-Gm-RC LPF 94
5.2.1 Filter architecture 96
7 p* k6 }  B7 }; a, B5.2.2 Automatic RC calibration scheme 97
5.2.3 Measurements results 102
( ?- ~! G  g4 b: l& ?  V# aContents ix
( x: ~( k( N% \4 v  ]% [5.3 LPF and VGA for SDR Front End 105
  s8 w6 y- Y! a. S. D6 C- m( g5.3.1 LPF and VGA architectures 107
" W+ n( Z- o$ E  ]+ a" o) p5.3.2 Prototype measurements 111
. S; U1 u. [  U$ f5.4 Conclusions 118
5 W* @8 A5 i% p  h0 ?0 [; lAcronyms 119
List of Figures 123
+ g1 y. w, s: ^6 o4 ]List of Tables 129
! n: c  d0 y: E6 f/ N% oReferences 131
" _: |; ^9 @; [4 PIndex 139