Advanced Analog Integrated Circuits. Precision Techniques

Transcription

1 Advanced Analog Integrated Circuits Precision Techniques Bernhard E. Boser University of California, Berkeley Copyright 2016 by Bernhard Boser 1

2 Topics Offset Drift 1/f Noise Mismatch 2

3 Motivation 3

4 Sources of Inaccuracies in ICs 4

5 Advanced Analog Integrated Circuits 1/f Noise Bernhard E. Boser University of California, Berkeley Copyright 2016 by Bernhard Boser 5

6 1/f Noise Spectrum 6

7 1/f Noise Other names: flicker noise, pink noise Caused by traps near Si/SiO2 interface Randomly capture and release carriers Less significant in BJT, JFET, bulk current flow (PMOS) Empirical models: D. Xie et al., SPICE Models for Flicker Noise in n-mosfets from Subthreshold to Strong Inversion, IEEE Trans. CAD, Nov 200, pp & i # $ = ( )* + $, -. / 0 $ K f is technology dependent, numbers for EE 240B: 180nm Process 65nm Process NMOS &7 A 9 F &7 A 9 F PMOS &7 A 9 F &7 A 9 F 7

8 1/f Noise Corner Frequency 8

9 1/f Noise Corner Frequency 9

10 Total 1/f Noise 10

11 Total 1/f versus Thermal Noise 11

12 MOS Model with Channel Noise Generator 12

13 Other MOSFET Noise Sources 13

14 Advanced Analog Integrated Circuits Shot Noise (Aside ) Bernhard E. Boser University of California, Berkeley boser@eecs.berkeley.edu Copyright 2016 by Bernhard Boser 14

15 Shot Noise in PN Junction 15

16 Shot Noise in BJTs 16

17 BJT Small Signal Noise Model 17

18 Advanced Analog Integrated Circuits Offset Bernhard E. Boser University of California, Berkeley Copyright 2016 by Bernhard Boser 18

19 Modeling Offset B. E. Boser 19

20 Sources of Error and Mitigation 20

21 Dynamic Offset Cancellation (DOC) Refs: [1] K. Makinwa, "Dynamic offset cancellation techniques in CMOS," ISSCC Tutorial, Feb (available from SSCS website). [2] C.C. Enz and G.C. Temes, Circuit techniques for reducing the effects of opamp imperfections: autozeroing, correlated double sampling and chopper stabilization, Proc. IEEE, Nov. 1996, pp

22 DOC Techniques Comparison 22

23 DOC versus Trimming 23

24 Advanced Analog Integrated Circuits Auto Zeroing Bernhard E. Boser University of California, Berkeley Copyright 2016 by Bernhard Boser 24

25 Auto-Zeroing Principle 25

26 Auto-Zero Phase F 1 (DC Analysis) 26

27 Amplification Phase F 2 (DC Analysis) 27

28 Advanced Analog Integrated Circuits Auto Zeroing Noise Analysis Bernhard E. Boser University of California, Berkeley Copyright 2016 by Bernhard Boser 28

29 What Happens to Noise? 29

30 Noise Transfer Function 30

31 Noise Transfer Function 31

32 Noise Spectrum at Output 32

33 Advanced Analog Integrated Circuits Auto Zeroing Charge Injection Bernhard E. Boser University of California, Berkeley Copyright 2016 by Bernhard Boser 33

34 Mitigating Charge Injection Error 34

35 Reducing Charge Injection Error (1) 35

36 Reducing Charge Injection Error (2) 36

37 Multistage Offset Cancellation 37

38 Multistage Offset Cancellation 38

39 Comparator Example 39

40 Comparator Example: Circuit Details 40

41 Auto-Zeroing Residual Offset 41

42 Advanced Analog Integrated Circuits Chopper Stabilization Bernhard E. Boser University of California, Berkeley Copyright 2016 by Bernhard Boser 42

43 Chopping Idea 43

44 Chopping Concept 44

45 Square Wave Modulator 45

46 Time Domain 46

47 Frequency Domain 47

48 Frequency Domain 48

49 Advanced Analog Integrated Circuits Chopper Noise Bernhard E. Boser University of California, Berkeley Copyright 2016 by Bernhard Boser 49

50 Residual In-Band Noise 50

51 Residual In-Band Noise 51

52 Example [ Enz 1996 ] 52

53 Two-Stage Chopper Amplifier 53

54 Folded Cascode with Chopper 54

55 Advanced Analog Integrated Circuits Chopper Nonidealities Bernhard E. Boser University of California, Berkeley Copyright 2016 by Bernhard Boser 55

56 Finite Amplifier Bandwidth 56

57 Clock Feedthrough 57

58 Summary of Chopper Design Considerations 58

59 Advanced Analog Integrated Circuits Advanced Chopping Techniques Bernhard E. Boser University of California, Berkeley Copyright 2016 by Bernhard Boser 59

60 Objectives 60

61 Nested Chopping [ Bakker 2000 ] 61

62 Spike Dead-Banding [ Menolfi 2001 ] 62

63 Spike Bandpass Filter [ Menolfi 1999 ] 63

64 Ripple Reduction with AC Coupling 64

65 Ripple Reduction with SC Filter [ Bakker 1997 ] 65

66 Ripple Reduction with Digital Filter 66

67 Advanced Analog Integrated Circuits Chopper Amplifier Performance Bernhard E. Boser University of California, Berkeley Copyright 2016 by Bernhard Boser 67

68 Offset Compensated OpAmps 68

69 Implementation Example 69

70 Chopping Summary 70

71 Advanced Analog Integrated Circuits Dynamic Element Matching Bernhard E. Boser University of California, Berkeley Copyright 2016 by Bernhard Boser 71

72 Application: Precision DAC 72

73 DEM Concept 73

74 DAC Application Example 74

75 Advanced Analog Integrated Circuits Temperature Sensor Example Bernhard E. Boser University of California, Berkeley Copyright 2016 by Bernhard Boser 75

76 CMOS Temperature Sensor [ Pertijs 2005 ] 76

77 Bandgap Temperature Sensing 77

78 Sensor Principle 78

79 A/D Conversion: SD Modulator 79

80 Temperature Sensor Block Diagram 80

81 (1) Accurate 1:p Ratio with DEM 81

82 Sigma-Delta Modulator 82

83 Sigma-Delta Circuit Implementation 83

84 Evaluation Other techniques used to get target performance: β insensitive generation curvature correction Nonlinear decimation filter averaging between Q / and Q G 84