About the Authors J.F. (Frerik) Witte was born in Amsterdam, the Netherlands, on March 16, 1979, where he lived until finishing his high school education (Atheneum) at the Pieter Nieuwland College in 1997. In that year he moved to Delft to start his studies in electrical engineering. He received his M.Sc. degree in electrical engineering (cum laude) from Delft University of Technology in 2003. The subject of his M.Sc. thesis was On-Chip Time References and Electro- Thermal Oscillators. In 2003, he started working towards a Ph.D. degree at the Electronic Instrumentation Laboratory of Delft University of Technology. The subject of his research was to design low-offset broadband CMOS amplifiers, which resulted in this book. From January to April 2003, he did an internship at Philips Semiconductors, San Jose, California, where he worked on integrated diagnostic circuits to measure the value of an external capacitor. Since January 2009, he is working as a senior design engineer for National Semiconductor at Delft. His professional interests include sensors, precision analog and mixed-signal design. He received the ESSCIRC 2006 Young Scientist Award. 163
About the Authors Kofi A. A. Makinwa received the B.Sc. and M.Sc. degrees from Obafemi Awolowo University, Ile-Ife, Nigeria, in 1985 and 1988, respectively, the M.E.E. degree from the Philips International Institute, Eindhoven, the Netherlands, in 1989, and the Ph.D. degree from Delft University of Technology, Delft, the Netherlands, in 2004. From 1989 to 1999, he was a Research Scientist with Philips Research Laboratories, where he designed sensor systems for interactive displays and analog front-ends for optical and magnetic recording systems. In 1999, he joined Delft University of Technology, where he is currently an professor with the Faculty of Electrical Engineering, Computer Science and Mathematics. His main research interests are in the design of precision analog circuitry, sigma-delta modulators and sensor interfaces. His work has resulted in ten U.S. patents and over 70 technical papers. Prof. Makinwa is on the program committees of several international conferences, including the IEEE International Solid-State Circuits Conference (ISSCC) and the International Solid-state Sensors and Actuators Conference (Transducers). He has given plenary talks and tutorials at several conferences, including twice at the ISSCC. He is a co-recipient of JSSC (2005), ISSCC (2008, 2006, 2005), ESSCIRC (2006) and ISCAS (2008) best paper awards. In 2005, he received the Veni Award from the Netherlands Organization for Scientific Research and the Simon Stevin Gezel Award from the Dutch Technology Foundation. He is a distinguished lecturer of the IEEE Solid-State Circuits Society and a fellow of the Young Academy of the Royal Netherlands Academy of Arts and Sciences. 164
Johan H. Huijsing was born on May 21, 1938. He received the M.Sc. degree in Electrical Engineering from the Delft University of Technology, Delft, the Netherlands in 1969, and the Ph.D. degree from this University in 1981 for his thesis on operational amplifiers. He has been an assistant and associate professor in Electronic Instrumentation at the Faculty of Electrical Engineering of the Delft University of Technology since 1969, where he became a full professor in the chair of Electronic Instrumentation since 1990, and professor-emeritus since 2003. From 1982 through 1983 he was a senior scientist at Philips Research Labs. in Sunnyvale, California, USA. From 1983 until 2005 he was a consultant for Philips Semiconductors, Sunnyvale, California, USA and since 1998 also a consultant for Maxim, Sunnyvale, California, USA. The research work of Johan Huijsing is focused on the systematic analysis and design of operational amplifiers, analog-to-digital converters and integrated smart sensors. He is author or co-author of some 250 scientific papers, 40 patents and 13 books, and co-editor of 13 books. As a professor he guided 27 Ph.D. students toward their degree. He is fellow of IEEE for contributions to the design and analysis of analog integrated circuits. He was awarded the title of Simon Stevin Meester for applied Research by the Dutch Technology Foundation. 165
Index 1 A auto-zero 14 23 auxiliary input stage 17 input offset storage 16 instrumentation amplifier 76 noise 19 output offset storage 15 B biasing constant current 141 constant transconductance 95 PTAT 140 PTIM 95 C charge injection 15, 17, 18, 27, 29, 31, 32, 33, 34, 35, 36, 37, 40 see also residual offset chopped auto-zero amplifier 29 31 chopper 23 29 amplifier 24 charge injection 27 29 feedback amplifier 26 instrumentation amplifier 75 noise 25 ripple 88 ripple reduction 88 chopper layout 158, 159 chopper offset-stabilized chopper amplifier 60, 82 common-mode feedback input controlled 111 long tailed pair 92, 109, 110 resistive 94, 142 continuous-time auto-zero see also offset-stabilization auto-zero 48 cross talk capacitors in choppers 27 29 current-feedback instrumentation amplifier 68 74 common-mode gain dependency 129, 146 current-sensing 129 133 D dynamic offset compensation see auto-zero see chopper see offset-stabilization F frequency compensation Miller 94 multi-path hybrid-double-nested Miller 52, 53 multi-path hybrid-nested 167
Index Miller 50, 51, 54, 55, 56, 57, 61, 88, 98, 104, 138 multi-path nested Miller 50 nested Miller 55 G gain-boosting 110 H high-side current-sensing 130 L low-side current-sensing 130 M mismatch 4 7 N noise effect of auto-zero on 19 23 effect of chopper and auto-zero offset-stabilization on 59 effect of chopper offset stabilization on 49 effect of chopper on 25 noise folding 19 23 O offset 3 minimizing 6 offset in CMOS amplifiers 3 offset-stabilization 45 59 auto-zero 47 chopper 48 chopper and auto-zero 58 chopper with ripple filter 55 58 concept 45 frequency compensation 50 instrumentation amplifier 79 81 iterative 61 on-chip coax 160 opamp class-a 94, 142 class-ab 92, 108 folded cascode 6, 92, 109 gain-boosted folded cascode 110 P ping-pong 44 45, 78 ping-pong-pang 78 79 PTAT current source 140 PTIM current source 95 R residual offset due to charge injection 15, 17, 18, 27, 88 due to chopped parasitic 54, 56, 89, 106, 120 due to finite gain 17, 18, 46, 47, 56, 57, 87 due to parasitics 28, 29, 156, 157 layout 156 162 ripple reduction 88 T threshold voltage mismatch 4, 5 transconductance factor mismatch 4, 5 168