pipelined analog-to-digital conversion using class-ab amplifiers

128 Pages·2010·3.1 MB·English

PIPELINED ANALOG-TO-DIGITAL CONVERSION
USING CLASS-AB AMPLIFIERS

A DISSERTATION
SUBMITTED TO THE DEPARTMENT OF ELECTRICAL ENGINEERING
AND THE COMMITTEE ON GRADUATE STUDIES
OF STANFORD UNIVERSITY
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY

Kyung Ryun Kim
December 2010
© 2011 by Kyung Ryun Kim. All Rights Reserved.

Re-distributed by Stanford University under license with the author.

This work is licensed under a Creative Commons Attribution-

Noncommercial 3.0 United States License.
http://creativecommons.org/licenses/by-nc/3.0/us/

This dissertation is online at: http://purl.stanford.edu/tn724tb5229

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I certify that I have read this dissertation and that, in my opinion, it is fully adequate
in scope and quality as a dissertation for the degree of Doctor of Philosophy.
Boris Murmann, Primary Adviser
I certify that I have read this dissertation and that, in my opinion, it is fully adequate
in scope and quality as a dissertation for the degree of Doctor of Philosophy.
S Wong
I certify that I have read this dissertation and that, in my opinion, it is fully adequate
in scope and quality as a dissertation for the degree of Doctor of Philosophy.
Bruce Wooley
Approved for the Stanford University Committee on Graduate Studies.
Patricia J. Gumport, Vice Provost Graduate Education
This signature page was generated electronically upon submission of this dissertation in
electronic format. An original signed hard copy of the signature page is on file in
University Archives.
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Abstract
In high-performance pipelined analog-to-digital converters (ADCs), the residue
amplifiers dissipate the majority of the overall converter power. Therefore, finding
alternatives to the relatively inefficient, conventional class-A circuit realization is an
active area of research. One option for improvement is to employ class-AB amplifiers,
which can, in principle, provide large drive currents on demand and improve the
efficiency of residue amplification. Unfortunately, due to the simultaneous demand for
high speed and high gain in pipelined ADCs, the improvements seen in class-AB
designs have so far been limited.
This dissertation presents the design of an efficient class-AB amplification
scheme based on a pseudo-differential, single-stage and cascode-free architecture. The
proposed amplifier exhibits fast turn-on and turn-off times, making it possible to apply
dynamic power cycling to further reduce power. Nonlinear errors due to finite DC
gain are addressed using a deterministic background calibration scheme that measures
the circuit imperfections in time intervals between normal conversion cycles of the
ADC. This proposed scheme also features a spline-based correction that handles the
measured errors based on piecewise polynomial functions.
As a proof of concept, a 12-bit 30-MS/s pipelined ADC was realized using class-
AB amplifiers with the proposed digital calibration. The prototype ADC occupies an
active area of 0.36 mm2 in 90-nm CMOS. It dissipates 2.95 mW from a 1.2-V supply
and achieves an SNDR of 64.5 dB for inputs near the Nyquist frequency. The
corresponding figure of merit is 72 fJ/conversion-step.

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Acknowledgments
It has been a great honor and a privilege to be a graduate student at Stanford
University. My experience at Stanford has been both tremendously educational and
enjoyable. During the six years of my stay, I have learned so many things from
professors and colleagues. From them, I not only have learned technical skills in the
area of engineering but also wisdoms for life. I wish to acknowledge many people for
giving me valuable lessons and joy during my life at Stanford.
First of all, I would like to thank Professor Boris Murmann for supervising my
doctoral research. Throughout my graduate program, he has been a great mentor and
supporter who gave me valuable advices without which none of my doctoral work
would have been possible. I learned how to design circuits and to conduct a quality
research from him. Whenever I encountered a problem along the way to the Ph.D., his
keen insights guided me to the right direction, and his engineering expertise provided
me with a new idea. Sincerely, working with him was the best part of my life at
Stanford.
I would like to extend my appreciation to my associate advisor, Professor Bruce A.
Wooley, and Professor S. Simon Wong for being my reading and oral examination
committee members. With great expertise, they gave me lots of technical feedbacks
and helped me consolidate my work. I also thank Professor Roger T. Howe for
chairing my oral examination committee and sharing his wisdoms of life. It is an
honor for me to have them all in my committee.
I would also like to give my sincere gratitude to Ms. Ann Guerra, who is our
group’s administrative assistant. I’m one of the many people who were touched by her
kindness. She helped me in many ways including, but not limited to, creating
important administrative forms or getting a reimbursement. She made such tasks
incomparably easier.
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For sponsorship, I thank Samsung Scholarship and the Stanford Initiative for
Rethinking Analog Design (RAD). I also thank United Microelectronics Corporation
(UMC) for the fabrication of the prototype chip.
I also thank Professor Murmann’s research group members, both past and present.
In particular, I thank Dr. Jung-Hoon Chun, Paul Wang Lee, Dr. Echere Iroaga, Dr.
Yangjin Oh, Dr. Jason Hu, Dr. Parastoo Nikaeen, Pedram Lajevardi, Dr. Clay Daigle,
Dr. Manar El-Chammas, Alireza Dastgheib, Donghyun Kim, Wei Xiong, Noam Dolev,
Drew Hall, Ray Nguyen, Ross Walker, Alex Guo, Yoonyoung Chung, Vaibhav
Tripathi, Martin Johannes Krämer, Bill Chen, Ryan Boesch, Man-Chia Chen,
Jonathon Spaulding and Alex Omid-Zohoor for technical discussions we shared and
all the feedbacks I received at the group meetings. I would also like to thank other
former and current colleagues in Allen building and Gates building for their technical
advices. This includes Dr. Haechang Lee, Dr. Jaeha Kim, Dr. Moonjung Kim, Dr.
Sangmin Lee, Dr. Hyunsik Park, Dr. Jim Salvia, Mohammad Hekmat, Roxana Trofin
Heitz, Henrique Miranda, Maryam Fathi, Dr. Sungbeom Park and Byongchan Lim.
I also thank friends who were always within close reach and made my life at
Stanford more enjoyable and memorable. In particular, I thank everyone from Korea
Advanced Institute of Science and Technology (KAIST) alumni community,
especially Seunghwa Ryu, Dr. Saeroonter Oh, Byungil Lee, Dr. Donghyun Kim and
Dr. Hyunwoo Nho. I also thank everyone from Cornerstone Community Church,
especially Jungjune Lee, Jeesoo Lee, Kyungmin Lim, Minyong Shin, Kibum Lee,
Wonhee Go, Jooeun Lee, Pastor Taegyun Sihn and Pastor Hun Sol. Last, I want to
thank Jaeyoung Lee for her kindness and affection.
Finally, I want to express my sincerest appreciation to my family. My father, Dr.
Kwon Jeep Kim, always encouraged and supported me throughout my life. He has
always enjoyed teaching me words of wisdom from history and the stories about great
thinkers and leaders, which gave me so many inspirations in my life. He also has been
a great role model for me. In particular, I grew up frequently watching my father read
and write books. This experience partly drove me to pursue this path. My mother, Sun
Ho Park, always showed me unconditional love and truly believed in me for my
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success. Her love and support brought out the best in me. Last, I’m also very grateful
to my sister, Ji Hye Kim. She has been very kind and loving to me and always has
been a great example for me to follow. My family has always given me love and
support without asking anything for return. This journey would not have been
successful, if it weren’t for their love and support. Therefore, I dedicate this
dissertation to my family.

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