High Gain Low Power Operational Amplifier Design and Compensation Techniques

147 Pages·2007·1.58 MB·English

by  Lisha Li

HIGH GAIN LOW POWER OPERATIONAL AMPLIFIER DESIGN
AND COMPENSATION TECHNIQUES
by
Lisha Li
A dissertation submitted to the faculty of
Brigham Young University
in partial fulfillment of the requirements for the degree of
Doctor of Philosophy
Department of Electrical and Computer Engineering
Brigham Young University
April 2007

Copyright c 2007 Lisha Li
(cid:13)
All Rights Reserved

BRIGHAM YOUNG UNIVERSITY
GRADUATE COMMITTEE APPROVAL
of a dissertation submitted by
Lisha Li
This dissertation has been read by each member of the following graduate committee
and by majority vote has been found to be satisfactory.
Date Donald T. Comer, Chair
Date David J. Comer
Date Doran K. Wilde
Date Richard L. Frost
Date D. J. Lee

BRIGHAM YOUNG UNIVERSITY
As chair of the candidate’s graduate committee, I have read the dissertation of Lisha
Li in its final form and have found that (1) its format, citations, and bibliographical
style are consistent and acceptable and fulfill university and department style require-
ments; (2) its illustrative materials including figures, tables, and charts are in place;
and (3) the final manuscript is satisfactory to the graduate committee and is ready
for submission to the university library.
Date Donald T. Comer
Chair, Graduate Committee
Accepted for the Department
Michael J. Wirthlin
Graduate Coordinator
Accepted for the College
Alan R. Parkinson
Dean, Ira A. Fulton College of
Engineering and Technology

ABSTRACT
HIGH GAIN LOW POWER OPERATIONAL AMPLIFIER DESIGN
AND COMPENSATION TECHNIQUES
Lisha Li
Department of Electrical and Computer Engineering
Doctor of Philosophy
This dissertation discusses and compares the existing compensation methods
for operational amplifiers. It explores a method to stabilize the op amps without
sacrificing bandwidth to the same degree that commonly used methods do. A cre-
ativedesignmethodologycombiningintuition,mathematicalanalysis,andmixedlevel
simulation is explored for the new compensation scheme. The mixed level approach,
associating system level simulation for most circuits along with device level simula-
tion for some critical analog circuit paths, is presented to verify the behavior of new
design concepts in an effective way. This approach also provides sufficient accuracy
to predict the circuit performance realistically. The new feedforward compensation
method overcomes the serious drawback of the widely used pole splitting method,
which greatly narrows the bandwidth. It can improve the phase margin as well as
optimize the bandwidth of the op amp. The proposed feedforward compensation
method can be easily applied to the popular two gain stage op amp architectures
with very little alteration.