Preface xiii
Overview of the Chapters
Unchanged from the second edition, the hierarchical organization of the third edition is illus-
trated in Table 1.1-2. Chapter 1 presents the material necessary to introduce CMOS analog
circuit design. This chapter gives an overview of the subject of CMOS analog circuit design,
defines notation and convention, makes a brief survey of analog signal processing, and gives
an example of analog CMOS design with emphasis on the hierarchical aspect of the design.
Chapters 2 and 3 form the basis for analog CMOS design by covering the subjects of CMOS
technology and modeling. Chapter 2 reviews CMOS technology as applied to MOS devices,
pn junctions, passive components compatible with CMOS technology, and other components
such as the lateral and substrate BJT and latch-up. Chapter 3 introduces the key subject of
modeling, which is used throughout the remainder of the text to predict the performance of
CMOS circuits. The focus of this chapter is to introduce a model that is good enough to pre-
dict the performance of a CMOS circuit to within ±10% to ±20% and will allow the design-
er insight and understanding. Computer simulation can be used to more exactly model the
circuits but will not give any direct insight or understanding of the circuit. The models in this
chapter include the MOSFET large-signal and small-signal models, including frequency
dependence. In addition, how to model the noise and temperature dependence of MOSFETs
and compatible passive elements is shown. This chapter also discusses computer simulation
models. This topic is far too complex for the scope of this book, but some of the basic ideas
are presented so that the reader can appreciate computer simulation models. Other models for
the subthreshold operation are presented along with how to use SPICE for computer simula-
tion of MOSFET circuits.
Chapters 4 and 5 present the topics of subcircuits and amplifiers that will be used to design
more complex analog circuits, such as an op amp. Chapter 4 covers the use of the MOSFET
as a switch followed by the MOS diode or active resistor. The key subcircuits of current
sinks/sources and current mirrors are presented next. These subcircuits permit the illustration
of important design concepts such as negative feedback, design trade-offs, and matching prin-
ciples. Finally, this chapter presents independent voltage and current references and the
bandgap voltage reference. These references attempt to provide a voltage or current that is
independent of power supply and temperature. Chapter 5 develops various types of amplifiers.
These amplifiers are characterized from their large-signal and small-signal performance,
including noise and bandwidth where appropriate. The categories of amplifiers include the
inverter, differential, cascode, current, and output amplifiers.
Chapters 6, 7, and 8 present examples of complex analog circuits. Chapter 6 introduces
the design of a simple two-stage op amp. This op amp is used to develop the principles of
compensation necessary for the op amp to be useful. The two-stage op amp is used to for-
mally present methods of designing this type of analog circuit. This chapter also examines the
design of cascode op amps, particularly the folded-cascode op amp. This chapter concludes
with a discussion of techniques to measure and/or simulate op amps. Chapter 7 presents the
subject of high-performance op amps. In this chapter various performances of the simple op
amp are optimized, quite often at the expense of other performance aspects. The topics
include buffered output op amps, high-frequency op amps, differential-output op amps, low-
power op amps, low-noise op amps, and low-voltage op amps. Chapter 8 presents the open-
loop comparator, which is an op amp without compensation. This is followed by methods of
designing this type of comparator for linear or slewing responses. Methods of improving the
performance of open-loop comparators, including autozeroing and hysteresis, are presented.
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