Advanced Analog Integrated Circuits Precision Techniques Bernhard E. Boser University of California, Berkeley boser@eecs.berkeley.edu Copyright 2016 by Bernhard Boser 1
Topics Offset Drift 1/f Noise Mismatch 2
Motivation 3
Sources of Inaccuracies in ICs 4
Advanced Analog Integrated Circuits 1/f Noise Bernhard E. Boser University of California, Berkeley boser@eecs.berkeley.edu Copyright 2016 by Bernhard Boser 5
1/f Noise Spectrum 6
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. 1293-1303. & i # $ = ( )* + $, -. / 0 $ K f is technology dependent, numbers for EE 240B: 180nm Process 65nm Process NMOS 4 10 6&7 A 9 F 6 10 6&7 A 9 F PMOS 2 10 6&7 A 9 F 3 10 6&7 A 9 F 7
1/f Noise Corner Frequency 8
1/f Noise Corner Frequency 9
Total 1/f Noise 10
Total 1/f versus Thermal Noise 11
MOS Model with Channel Noise Generator 12
Other MOSFET Noise Sources 13
Advanced Analog Integrated Circuits Shot Noise (Aside ) Bernhard E. Boser University of California, Berkeley boser@eecs.berkeley.edu Copyright 2016 by Bernhard Boser 14
Shot Noise in PN Junction 15
Shot Noise in BJTs 16
BJT Small Signal Noise Model 17
Advanced Analog Integrated Circuits Offset Bernhard E. Boser University of California, Berkeley boser@eecs.berkeley.edu Copyright 2016 by Bernhard Boser 18
Modeling Offset B. E. Boser 19
Sources of Error and Mitigation 20
Dynamic Offset Cancellation (DOC) Refs: [1] K. Makinwa, "Dynamic offset cancellation techniques in CMOS," ISSCC Tutorial, Feb. 2007 (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. 1584-1614. 21
DOC Techniques Comparison 22
DOC versus Trimming 23
Advanced Analog Integrated Circuits Auto Zeroing Bernhard E. Boser University of California, Berkeley boser@eecs.berkeley.edu Copyright 2016 by Bernhard Boser 24
Auto-Zeroing Principle 25
Auto-Zero Phase F 1 (DC Analysis) 26
Amplification Phase F 2 (DC Analysis) 27
Advanced Analog Integrated Circuits Auto Zeroing Noise Analysis Bernhard E. Boser University of California, Berkeley boser@eecs.berkeley.edu Copyright 2016 by Bernhard Boser 28
What Happens to Noise? 29
Noise Transfer Function 30
Noise Transfer Function 31
Noise Spectrum at Output 32
Advanced Analog Integrated Circuits Auto Zeroing Charge Injection Bernhard E. Boser University of California, Berkeley boser@eecs.berkeley.edu Copyright 2016 by Bernhard Boser 33
Mitigating Charge Injection Error 34
Reducing Charge Injection Error (1) 35
Reducing Charge Injection Error (2) 36
Multistage Offset Cancellation 37
Multistage Offset Cancellation 38
Comparator Example 39
Comparator Example: Circuit Details 40
Auto-Zeroing Residual Offset 41
Advanced Analog Integrated Circuits Chopper Stabilization Bernhard E. Boser University of California, Berkeley boser@eecs.berkeley.edu Copyright 2016 by Bernhard Boser 42
Chopping Idea 43
Chopping Concept 44
Square Wave Modulator 45
Time Domain 46
Frequency Domain 47
Frequency Domain 48
Advanced Analog Integrated Circuits Chopper Noise Bernhard E. Boser University of California, Berkeley boser@eecs.berkeley.edu Copyright 2016 by Bernhard Boser 49
Residual In-Band Noise 50
Residual In-Band Noise 51
Example [ Enz 1996 ] 52
Two-Stage Chopper Amplifier 53
Folded Cascode with Chopper 54
Advanced Analog Integrated Circuits Chopper Nonidealities Bernhard E. Boser University of California, Berkeley boser@eecs.berkeley.edu Copyright 2016 by Bernhard Boser 55
Finite Amplifier Bandwidth 56
Clock Feedthrough 57
Summary of Chopper Design Considerations 58
Advanced Analog Integrated Circuits Advanced Chopping Techniques Bernhard E. Boser University of California, Berkeley boser@eecs.berkeley.edu Copyright 2016 by Bernhard Boser 59
Objectives 60
Nested Chopping [ Bakker 2000 ] 61
Spike Dead-Banding [ Menolfi 2001 ] 62
Spike Bandpass Filter [ Menolfi 1999 ] 63
Ripple Reduction with AC Coupling 64
Ripple Reduction with SC Filter [ Bakker 1997 ] 65
Ripple Reduction with Digital Filter 66
Advanced Analog Integrated Circuits Chopper Amplifier Performance Bernhard E. Boser University of California, Berkeley boser@eecs.berkeley.edu Copyright 2016 by Bernhard Boser 67
Offset Compensated OpAmps 68
Implementation Example http://electronicdesign.com/analog/chopper-stabilized-op-amps 69
Chopping Summary 70
Advanced Analog Integrated Circuits Dynamic Element Matching Bernhard E. Boser University of California, Berkeley boser@eecs.berkeley.edu Copyright 2016 by Bernhard Boser 71
Application: Precision DAC 72
DEM Concept 73
DAC Application Example 74
Advanced Analog Integrated Circuits Temperature Sensor Example Bernhard E. Boser University of California, Berkeley boser@eecs.berkeley.edu Copyright 2016 by Bernhard Boser 75
CMOS Temperature Sensor [ Pertijs 2005 ] 76
Bandgap Temperature Sensing 77
Sensor Principle 78
A/D Conversion: SD Modulator 79
Temperature Sensor Block Diagram 80
(1) Accurate 1:p Ratio with DEM 81
Sigma-Delta Modulator 82
Sigma-Delta Circuit Implementation 83
Evaluation Other techniques used to get target performance: β insensitive I @ABC generation V @E curvature correction Nonlinear decimation filter V @E averaging between Q / and Q G 84