Understanding DeltaSigma Data ConvertersISBN: 9780471465850
464 pages
November 2004, WileyIEEE Press

Description
Understanding DeltaSigma Data Converters brings readers a clear understanding of the principles of deltasigma (DeltaSigma) converter operationanalog to digital and digital to analog. It introduces the best computeraided analysis and design techniques available. With an understanding of the great versatility of the DeltaSigma converter, readers can apply their new knowledge to a wide variety of applications, including digital telephony, digital audio, wireless and wired communications, medical electronics, and industrial and scientific instrumentation. The authors make the material accessible to all design engineers by focusing on developing an understanding of the physical operation rather than getting mired in complex mathematical treatments and derivations.
Written for entrylevel readers, the publication has a natural flow that begins with basic concepts, enabling the readers to develop a solid foundation for the book's more complex material. The text, therefore, starts with a general introduction to the DeltaSigma converter, including a brief historical overview to place it in context. Next, the publication introduces the firstorder DeltaSigma modulator, covering oversampling, noiseshaping, decimation filtering and other key concepts. Then, using the firstorder modulator as a foundation, second and higherorder modulators are presented and analyzed. Finally, the authors delve into implementation considerations and present several design examples using the DeltaSigma Toolbox.
Everything needed to facilitate quick comprehension and help readers apply their newly learned principles is provided:Simplified methods to understand complicated concepts such as spectral estimation and switched noiseReferences that lead to indepth analysis of specialized topicsFigures and charts that illustrate complex design issuesConclusion section at the end of each chapter that highlights the key pointsReference manual for the DeltaSigma Toolbox, along with numerous practical examples that illustrate the use of the Toolbox
This is essential reading for all design engineers who want to learn and fully harness the powerful capabilities of DeltaSigma data converters. Upperlevel undergraduates and graduate students will find the book's logical organization and clear style, coupled with numerous practical examples, a great entry into the field.
Table of Contents
Foreword xi
References xii
Chapter 1 Introduction 1
1.1 The Need for Oversampling Converters 1
1.2 Delta and DeltaSigma Modulation 4
1.3 HigherOrder SingleStage NoiseShaping Modulators
1.4 MultiStage (Cascade, MASH) Modulators 10
1.5 Bandpass ΔΣ Modulators 13
1.6 ΔΣ Modulators with MultiBit Quantizers 15
1.7 DeltaSigma DigitaltoAnalog Converters 16
1.8 History; Performance and Architecture Trends 17
CHAPTER 2 The FirstOrder Delta Sigma Modulator 21
2.1 Quantizers and Quantization Noise 21
2.1.1 Binary Quantization 28
2.2 MODI as an ADC 29
2.3 MODI as a DAC 34
2.4 MODI Linear Model 36
2.5 Simulation of MODI 38
2.6 MODI under DC Excitation 41
2.6.1 Idle Tone Generation 42
2.6 2 Graphical Visualization 45
2.7 Stability of MODI 49
2.8 The Effects of Finite OpAmp Gain 50
2.8.1 Linear Systems Perspective Degraded Noise Shaping 50
2.8.2 Nonlinear Systems Perspective Dead Zones 51
2.9 Decimation Filters for MODI 54
2.9.1 The Sine Filter [9] 55
2.9.2 The Sine1 Filter 58
2.10 Conclusions 60
CHAPTER 3 The SecondOrder DeltaSigma Modulator 63
3.1 The SecondOrder Modulator: MOD2 63
3.2 Simulation of MOD2 67
3.3 Nonlinear Effects in MOD2 71
3.3 1 Signaldependent quantizer gain 71
3.3.2 Stability o/MOD2 74
3.3.3 Deadband behavior 77
3.4 Alternative SecondOrder Modulator Structures 79
3.4.1 The Boser Wooley Modulator 79
3.4.2 The SilvaSteensgaard Structure 80
3.4.3 The ErrorFeedback Structure 81
3.4.4 Generalized SecondOrder Structures 82
3.4.5 Optimal SecondOrder Modulator 84
3.5 Decimation Filtering for SecondOrder ΔΣ Modulators 86
3.6 Conclusions 89
CHAPTER 4 HigherOrder DeltaSigma Modulation 91
4.1 HighOrder SingleQuantizer Modulators 91
4.2 Stability Considerations in HighOrder Modulators 97
4.2.1 SingleBit Modulators 98
4.2.2 MultiBit Modulators [12] 104
4.3 Optimization of the NTF Zeros and Poles 107
4.3.1 NTF Zero Optimization 107
4.3.2 NTF Pole Optimization 111
4.4 Loop Filter Architectures 115
4.4.1 Loop Filters with Distributed Feedback and Input Coupling The CIFB and CRFB Structures 115
4.4.2 Loop Filters with Distributed Feedforward and Input Coupling The CIFF and CRFF Structures 121
4.5 MultiStage Modulators 122
4.5.1 The LeslieSingh (L0 Cascade) Structure [16] 123
4.5.2 Cascade (MASH) Modulators 127
4.5.3 Noise Leakage in Cascade Modulators 132
4.6 Conclusions 136
CHAPTER 5 Bandpass and Quadrature DeltaSigma Modulation 139
5.1 The Need for Bandpass and Quadrature Modulation 139
5.2 Bandpass NTF Selection 145
5.2.1 Pseudo Npath transformation 149
5.3 Architectures for Bandpass DeltaSigma Modulators 151
5.3.1 Topology Choices 151
5.3.2 Resonator Implementations 154
5.4 Bandpass Modulator Example 161
5.5 Quadrature Signals 166
5.6 Quadrature Modulation 172
5.7 Conclusions 176
CHAPTER 6 Implementation Considerations For AZ ADCs 179
6.1 Modulators with MultiBit Internal Quantizers 179
6.2 DualQuantizer Modulators 182
6.2.1 DualQuantization MASH Structure 182
6.2.2 DualQuantization SingleStage Structure 183
6.3 Dynamic Element Randomization 184
6.4 Mismatch Error Shaping 186
6.4.1 Element Rotation or DataWeighted Averaging 189
6.4.2 Individual Level Averaging 191
6.4.3 VectorBased Mismatch Shaping 192
6.4.4 Element Selection Using a Tree Structure 196
6.5 Digital Correction of DAC Nonlinearity 199
6.5.1 DigitallyCorrected MultiBit AS Modulator with PowerUp Calibration 200
6.5.2 DigitallyCorrected MultiBit AS ADC with Background Calibration 202
6.6 ContinuousTime Implementations 205
6.6.1 A ContinuousTime Implementation ofMOD2 207
6.6.2 Inherent AntiAliasing in CT AS ADCs 212
6.6.3 Design Issues for ContinuousTime Modulators 213
6.7 Conclusions 216
CHAPTER 7 DeltaSigma DACs 219
7.1 System Architectures for ΔΣ DACs 220
7.2 Loop configurations for ΔΣ DACs 222
7.2.1 SingleStage DeltaSigma Loops 223
7.2.2 The Error Feedback Structure 224
7.2.3 Cascade (MASH) Structures 226
7.3 ΔΣ DACs Using MultiBit Internal DACs 229
7.3.1 DualTruncation DAC Structures 230
7.3.2 Multibit DeltaSigma DACs with Mismatch Error Shaping 232
7.3.3 Digital Correction of MultiBit DeltaSigma DACs 236
7.3.4 Comparison of SingleBit and MultiBit ΔΣ DACs 238
7.4 Interpolation Filtering for ΔΣ DACs 239
7.5 Analog PostFilters for ΔΣ DACs 243
7.5.1 Analog PostFiltering in SingleBit ΔΣ DACs 244
7.5.2 Analog PostFiltering in MultiBit ΔΣ DACs 251
7.6 Conclusions 253
CHAPTER 8 HighLevel Design and Simulation 257
8.1 NTF Synthesis 257
8.1.1 How synthesize NTF works 260
8.1.2 Limitations of synthes i zeNTF 262
8.2 NTF Simulation, SQNR Calculation and Spectral Estimation 263
8.3 NTF Realization and Dynamic Range Scaling 266
8 3.1 The ABCD Matrix 271
8.4 Creating a SPICESimulatable Schematic 273
8.4.1 Voltage Scaling 273
8.4.2 Timing 274
8.4.3 kT/C Noise 280
8.5 Conclusions 281
CHAPTER 9 Example Modulator Systems 283
9.1 SCMOD2: GeneralPurpose SecondOrder SwitchedCapacitor ADC 283
9.1.1 System Design 284
9.1.2 Timing 286
9.1.3 Scaling 288
9.1.4 Verification 289
9.1.5 Capacitor Sizing 292
9.1.6 Circuit Design 294
9.2 SCM0D5: A FifthOrder SingleBit NoiseShaping Loop 298
9.2.1 NTF and Architecture Selection 298
9.2.2 Implementation 302
9.2.3 Instability and Reset 311
9.3 A Wideband 20 Cascade System 311
9.3.1 Architecture 312
9.3 2 Implementation 315
9.4 A Micropower ContinuousTime ADC 317
9.4.1 HighLevel Design 318
9.4.2 Circuit Design 322
9.5 A ContinuousTime Bandpass ADC 326
9.5.1 Architecture/Analysis 328
9.5.2 Subcircuits 333
9.6 Audio DAC 337
9.6.1 Modulator Design 338
9.6.2 Interpolation Filter Design 344
9.6.3 DAC and Reconstruction Filter Design 355
9.7 Conclusions 357
9.7.1 The ADC StateoftheArt 357
9.7.2 FOM Justification 359
9.7.2 References 362
APPENDIX A Spectral Estimation 365
A.I Windowing 366
A.2 Scaling and Noise Bandwidth 373
A.3 Averaging 377
A.4 An Example 379
A.5 Mathematical Background 383
APPENDIX B The DeltaSigma Toolbox 389
Demonstrations and Examples 390
Summary of Key Functions 391
synthesizeNTF 393
predictSNR 395
simulateDSM 396
simulateSNR 398
realizeNTF 400
stuffABCD, mapABCD 401
scaleABCD 402
calculateTF 403
sirnulateESL 404
designHBF 405
simulateHBF 408
findPIS 409
Modulator Model Details 410
APPENDIX C Noise in SwitchedCapacitor DeltaSigma Data Converters 417
C.I Noise Effects in CMOS Op Amps 419
C.2 Sampled Thermal Noise 423
C.3 Noise Effects in an SC Integrator 425
C.4 Integrator Noise Analysis Example 433
C.5 Noise Effects in DeltaSigma ADC Loops 435
Author Information
GABOR C. TEMES, PhD, is a Professor in the Department of Electrical and Computer Engineering at Oregon State University. He is a Life Fellow of the IEEE and a recipient of the 1998 IEEE Graduate Teaching Award.
Reviews
"...a 'onestop shop' for engineers who want a comprehensive introduction...an excellent starting point for engineers entering the field, as well as a useful reference for experts." (IEEE SolidState Circuits Society Newsletter, September 2005)
"…a comprehensible tutorial describing the design of baseband, bandpass, and quadrature deltasigma modulators…" (CHOICE, April 2005)