PhaseLock Techniques 3rd Edition:PHASELOCK TECHNIQUES
Third Edition
FLOYD M. GARDNER
Consulting Engineer
Palo Alto, California CONTENTS1 INTRODUCTION 1
1.1 Salient Properties of PLLs / 2
1.1.1 Bandwidth / 2
1.1.2 Linearity / 3
1.2 Organization of the Book / 3
1.3 Annotated Bibliography / 3
1.3.1 Books / 3
1.3.2 Reprint Volumes / 4
1.3.3 Journal Special Issues / 5
2 TRANSFER FUNCTIONS OF ANALOG PLLs 6
2.1 Basic Transfer Functions / 6
2.1.1 Transfer Functions of Individual Elements / 7
2.1.2 Combined Transfer Functions / 8
2.1.3 Characteristic Equation / 9
2.1.4 Nomenclature, Coefficients, and Units / 9
2.2 Second-Order PLLs / 10
2.2.1 Loop Filters / 10
2.2.2 Order and Type / 12
vii
viii CONTENTS
2.2.3 Loop Parameters / 12
2.2.4 Frequency Response / 15
2.3 Other Loop Types and Orders / 20
2.3.1 General Definition of Loop Gain K / 20
2.3.2 Examples of Type 1 PLLs / 22
2.3.3 Examples of Type 2 PLLs / 24
2.3.4 Higher-Type PLLs / 28
Reference / 28
3 GRAPHICAL AIDS 29
3.1 Root-Locus Plots / 30
3.1.1 Description of Root-Locus Plots / 30
3.1.2 Stability Criterion / 33
3.1.3 Root Loci of Type 1 PLLs / 33
3.1.4 Root Loci of Type 2 PLLs / 33
3.1.5 Root Loci of Type 3 PLLs / 34
3.1.6 Root Loci of Higher-Order PLLs / 35
3.1.7 Effect of Loop Delay on Root Locus / 38
3.2 Bode Plots / 38
3.2.1 Presentation Options / 38
3.2.2 Stability / 39
3.2.3 Bode Plots of Type 1 PLLs / 40
3.2.4 Bode Plots of Type 2 PLLs / 43
3.2.5 Bode Plots of Type 3 PLLs / 48
3.3 Nyquist Diagrams / 49
3.4 Nichols Charts / 49
3.4.1 Stability Criterion / 49
3.4.2 M-Contours / 50
3.4.3 Examples of Nichols Charts / 50
3.5 Closed-Loop Frequency-Response Curves / 52
Appendix 3A: Salient Features of Root Loci / 52
3A.1 Branches of Root Loci / 53
3A.2 Locus on the Real Axis / 53
3A.3 Locus Intersections with Axes / 54
Appendix 3B: Formats of the Open-Loop Transfer Function
G(s) / 56
3B.1 Proportional-Plus-Integral Section / 56
3B.2 High-Frequency Section / 60
3B.3 Calculations / 60
CONTENTS ix
Appendix 3C: Closed-Loop Frequency Responses / 61
3C.1 Frequency-Response Formulas / 61
3C.2 Example Frequency-Response Graphs / 61
References / 64
4 DIGITAL PLLs: TRANSFER FUNCTIONS AND
RELATED TOOLS 65
4.1 Distinctive Properties of Digital PLLs / 65
4.2 Digital Transfer Function / 66
4.2.1 Configuration of a Digital PLL / 66
4.2.2 Difference Equations / 67
4.2.3 z-Transforms of the Loop Elements / 69
4.2.4 Loop Filter / 70
4.2.5 Loop Transfer Functions / 71
4.2.6 Poles and Zeros / 71
4.3 Loop Stability / 73
4.3.1 Type 1 DPLLs / 73
4.3.2 Type 2 DPLLs / 73
4.3.3 Type 3 DPLLs / 74
4.4 Root-Locus Plots / 74
4.4.1 Root Loci of Type 1 DPLLs / 75
4.4.2 Root Loci of Type 2 DPLLs / 75
4.4.3 Root Loci of Type 3 DPLLs / 78
4.5 DPLL Frequency Responses: Formulation / 79
4.6 Bode Plots and Nichols Charts / 80
4.6.1 Basis of Bode Plots / 80
4.6.2 Bode Stability Criteria / 81
4.6.3 Bode Plots of Example DPLLs / 81
4.6.4 Nichols Chart Example / 83
4.7 Time-Continuous Approximation for a DPLL / 85
4.8 Frequency-Response Examples / 86
4.8.1 Effect of Delay / 86
4.8.2 Effect of Bandwidth / 87
4.9 Lowpass Filters in the Loop / 88
4.9.1 Infinite Impulse Response Lowpass Filter / 88
4.9.2 Finite Impulse Response Lowpass Filter / 90
Appendix 4A: Stability of Digital Phaselock Loops / 91
4A.1 Type 1 DPLL / 92
4A.2 Type 2 DPLL / 93
Reference / 96
x CONTENTS
5 TRACKING 97
5.1 Linear Tracking / 97
5.1.1 Steady-State Phase Errors / 98
5.1.2 Transient Response / 100
5.1.3 Response to Sinusoidal Angle Modulation / 109
5.2 Nonlinear Tracking: Lock Limits / 112
5.2.1 Phase-Detector Nonlinearity / 112
5.2.2 Steady-State Limits / 112
5.2.3 Transient Limits / 114
5.2.4 Modulation Limits / 118
References / 121
6 EFFECTS OF ADDITIVE NOISE 123
6.1 Linear Operation / 123
6.1.1 Noise Model of a Phase Detector / 123
6.1.2 Noise Transfer Function / 129
6.1.3 Noise Bandwidth / 129
6.1.4 Signal-to-Noise Ratio in a PLL / 131
6.1.5 Optimality / 132
6.2 Nonlinear Operation / 132
6.2.1 Observed Behavior / 133
6.2.2 Nonlinear Analysis of Phase Error / 135
6.2.3 Probability Density and Variance / 136
6.2.4 Cycle Slips / 137
6.2.5 Experimental and Simulation Results / 138
6.2.6 Approximate Analyses / 138
6.2.7 Miscellaneous Features / 139
References / 141
7 EFFECTS OF PHASE NOISE 143
7.1 Properties of Phase Noise / 144
7.1.1 Oscillator Model / 144
7.1.2 Neglect of Amplitude Noise / 144
7.1.3 Variance / 144
7.1.4 Nonstationarity / 144
7.2 Spectra of Phase Noise / 146
7.2.1 Theoretical Spectrum Wvo(f ) / 146
7.2.2 Normalized Spectrum L(f ) / 147
7.2.3 RF Spectra WRF(f ) and PRF(f ) / 147
7.2.4 Phase-Noise Spectrum Wφ(f ) / 149
CONTENTS xi
7.2.5 Frequency-Noise Spectrum Wω(f ) / 152
7.2.6 Example Phase-Noise Spectrum / 152
7.3 Properties of Phase-Noise Spectra / 153
7.3.1 Typical Continuous Spectra / 154
7.3.2 Meaning of Wφ(f ) / 155
7.3.3 Interpretation of Spectral Displays / 156
7.3.4 Relationship Between Wφ(f ) and L(f ) / 157
7.4 Propagation of Phase Noise / 159
7.4.1 Phase-Noise Propagation in Auxiliary
Devices / 159
7.4.2 Phase-Noise Propagation in PLLs / 161
7.5 Integrated Phase Noise in PLLs / 162
7.5.1 Basic Formulas / 162
7.5.2 Excessive Phase Noise / 163
7.5.3 Effect on Coherent Demodulation / 163
7.5.4 Bandwidth Trade-off / 163
7.5.5 Integration / 164
7.5.6 A Paradox / 165
7.5.7 Integration of Spectral Lines / 166
7.5.8 Phase-Noise Specifications / 166
7.6 Timing Jitter / 167
Appendix 7A: Analysis of Interference in a Hard
Limiter / 168
Appendix 7B: Integrals of Untracked Phase Noise / 169
7B.1 Integration Procedures / 169
7B.2 Results of Integrations / 169
7B.3 Discussion / 171
Appendix 7C: Numerical Integration of PLL Phase
Noise / 171
7C.1 Definition and Application of Integrated Phase
Noise / 172
7C.2 Data Formats / 172
7C.3 Data Adjustments / 173
7C.4 Data Filtering / 174
7C.5 Numerical Integration / 174
Appendix 7D: Integration of Discrete Lines in the
Phase-Noise Spectrum / 175
Appendix 7E: Timing Jitter / 177
7E.1 Jitter Definitions / 177
7E.2 Jitter in PLLs / 179
References / 180
xii CONTENTS
8 ACQUISITION OF PHASELOCK 183
8.1 Characterization / 183
8.2 Phase Acquisition / 184
8.2.1 First-Order Loop / 184
8.2.2 Hang-up / 186
8.2.3 Lock-in / 186
8.2.4 Aided Phase Acquisition / 188
8.3 Frequency Acquisition / 189
8.3.1 Frequency Pull-in / 189
8.3.2 Frequency Sweeping / 195
8.3.3 Discriminator-Aided Frequency Acquisition / 199
8.3.4 Implementation of Frequency
Discriminators / 203
8.4 Diverse Matters / 204
8.4.1 Lock Indicators / 204
8.4.2 Wide-Bandwidth Methods / 205
8.4.3 Memory / 206
References / 206
9 OSCILLATORS 209
9.1 Desired Properties / 209
9.2 Classes of Oscillators / 210
9.3 Phase Noise in Oscillators: Simplified Approach / 210
9.3.1 Leeson’s Model / 210
9.3.2 Guides for Oscillator Design / 212
9.3.3 Example Phase-Noise Spectra / 213
9.3.4 Shortcomings of Leeson’s Model / 214
9.4 Classifications of Oscillators / 215
9.5 Phase Noise in Oscillators: Advanced Analysis / 217
9.5.1 Impulse Sensitivity Function / 218
9.5.2 Nonlinear Analyses for Phase Noise / 219
9.6 Other Disturbances / 221
9.7 Types of Oscillator Tuning / 223
9.7.1 Continuous-Tuning Oscillators / 223
9.7.2 Discrete-Tuning Oscillators / 224
9.8 Tuning of Analog VCOs / 226
9.8.1 Tuning Curve / 227
9.8.2 Tuning Methods / 228
9.8.3 Speed of Tuning / 231
References / 232
CONTENTS xiii
10 PHASE DETECTORS 237
10.1 Multiplier Phase Detectors / 237
10.1.1 Switching Phase Detectors: Principles / 238
10.1.2 Switching Phase Detectors: Examples / 240
10.1.3 Hybrid-Transformer PD / 244
10.1.4 Nonsinusoidal s-Curves / 245
10.2 Sequential Phase Detectors / 246
10.3 Phase/Frequency Detector / 248
10.3.1 PFD Configuration / 248
10.3.2 Delay in PFD / 250
10.3.3 PFD State Diagram / 251
10.3.4 PFD s-Curve / 252
10.3.5 Frequency Detection in a PFD / 253
10.3.6 Effects of Delay in a PFD / 254
10.3.7 Extra or Missed Transitions / 255
10.3.8 Lock Indicator for a PFD / 256
10.4 Behavior of Phase Detectors in Noise / 256
10.4.1 Bandpass Limiters / 256
10.4.2 Phase-Detector Noise Threshold / 258
10.4.3 s-Curve Shape in Noise / 259
10.4.4 Jitter Dependence on s-Curve Shape / 260
10.5 Two-Phase (Complex) Phase Detectors / 260
Appendix 10A: Phase Modulation Due to Phase-Detector
Ripple / 262
10A.1 Ripple Model / 262
10A.2 Basis of Analysis / 263
10A.3 Ripple Examples / 263
10A.4 Ripple Filters / 264
References / 265
11 LOOP FILTERS 267
11.1 Active vs. Passive Loop Filters / 267
11.2 DC Offset / 268
11.3 Transient Overload / 269
11.3.1 Overload from PD Ripple / 269
11.3.2 Overload During Acquisition / 269
12 CHARGE-PUMP PHASELOCK LOOPS 271
12.1 Model of a Charge Pump / 271
12.2 Loop Filter / 273
xiv CONTENTS
12.3 Static Phase Error / 274
12.4 Stability Issues / 275
12.5 Nonlinearities / 276
12.6 Ripple Suppression / 278
12.7 Late Developments / 280
References / 281
13 DIGITAL (SAMPLED) PHASELOCK LOOPS 282
13.1 QuasiLinear Sampled PLLs / 283
13.1.1 Digital-Controlled Oscillators / 283
13.1.2 Hybrid Phase Detectors / 286
13.1.3 Complex-Signal Digital Phase Detector / 289
13.1.4 DPLLs in Digital Data Receivers / 290
13.1.5 Loop Stability / 294
13.2 Quantization / 294
13.2.1 Lessons from Related Studies / 294
13.2.2 Quantization Considerations in Hybrid PLLs / 295
13.2.3 Effects of Frequency (NCO) Quantization / 296
13.2.4 Quantization in a Phase Detector and an
Integrator / 311
13.3 Irremediably Nonlinear PLLs / 312
13.3.1 Configuration of a Nonlinear PLL / 312
13.3.2 Operation of the PLL Elements / 314
13.3.3 PLL State Diagrams / 317
13.3.4 Operation of the Nonlinear PLL / 319
13.3.5 Type 2 Nonlinear PLL / 322
13.3.6 Effects of Additive Noise / 324
13.3.7 Application to Bit Synchronizers / 326
Appendix 13A: Transfer Function of a Multirate
DPLL / 327
13A.1 Nomenclature / 327
13A.2 Phase-Detector Operation / 327
13A.3 Accumulate & Dump and the Loop Filter / 327
13A.4 Hold Process / 328
13A.5 NCO, Phase Rotator, and M : 1
Down-Sampling / 329
13A.6 Transfer Functions / 330
13A.7 Transfer Function of a Hold Filter / 332
References / 333
CONTENTS xv
14 ANOMALOUS LOCKING 336
14.1 Sidelocks / 336
14.1.1 Periodic Modulations / 337
14.1.2 Cyclostationary Modulations / 338
14.1.3 Alias Locks / 340
14.2 Harmonic Locks / 341
14.3 Spurious Locks / 342
14.4 False Locks / 343
14.4.1 IF Filter Analysis / 344
14.4.2 Origin of False Locks / 346
14.4.3 False-Lock Properties / 348
14.4.4 Remedies for False Lock / 351
14.5 Lock Failures in Chains of PLLs / 353
References / 354
15 PLL FREQUENCY SYNTHESIZERS 357
15.1 Synthesizer Configurations / 357
15.1.1 Basic Configuration / 357
15.1.2 Alternative Configurations / 359
15.2 Frequency Dividers / 360
15.2.1 Analog Frequency Dividers / 361
15.2.2 Digital Counters as Frequency Dividers / 361
15.3 Fractional-N Counters / 362
15.3.1 Dual-Modulus Counters / 362
15.3.2 Fractional-N PLLs with Analog
Compensation / 364
15.3.3 Fractional-N PLLs with Delta–Sigma
Modulators / 366
15.4 Noise Propagation in a PLL / 369
15.4.1 Transfer Functions for Oscillator Noise / 369
15.4.2 Bandwidth Trade-off / 371
15.4.3 Other Noise Sources / 373
References / 376
16 PHASELOCK MODULATORS AND DEMODULATORS 380
16.1 Phaselock Modulators / 380
16.1.1 Modulator Fundamentals / 381
16.1.2 PLL Measurements via Modulations / 382
16.1.3 Delta–Sigma PLL Modulators / 382
xvi CONTENTS
16.2 Phaselock Demodulators / 383
16.2.1 PLLs for AM Demodulation / 383
16.2.2 Phase Demodulation / 386
16.2.3 Frequency Demodulation / 388
16.2.4 FM Noise / 389
16.3 FM Threshold / 391
16.3.1 Threshold Characterization / 391
16.3.2 FM Clicks / 393
16.3.3 Clicks in PLD / 395
16.3.4 Formal Optimization / 402
16.3.5 Modified PLD / 403
16.3.6 FM PLD Threshold: Summary / 405
References / 406
17 MISCELLANEOUS APPLICATIONS OF
PHASELOCK LOOPS 408
17.1 Synchronization of Data Signals / 408
17.2 Network Clocks / 409
17.3 Various Locked Oscillators / 409
17.3.1 Oscillator Stabilization / 410
17.3.2 Frequency-Multiplier PLLs / 411
17.3.3 Frequency-Translation PLLs / 411
17.4 PLLs in Television Receivers / 414
17.5 PLLs in Digital Systems / 414
17.5.1 Compensation of Timing Skew / 414
17.5.2 Jitter Attenuators / 414
17.6 PLLs for Motor Speed Control / 416
17.6.1 Basic Operation / 416
17.6.2 Electromechanical Considerations / 417
17.6.3 Alternative Configurations / 417
References / 418
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