High Frequency Continuous Time Filters in Digital CMOS Processes

✍ Scribed by Shanthi Pavan, Yannis Tsividis (auth.)

• Publisher: Springer US
• Year: 2002
• Tongue: English
• Leaves: 227
• Edition: 1
• Category: Library

✦ Synopsis

There is an ever increasing trend towards putting entire systems on a single chip. This means that analog circuits will have to coexist on the same substrate along with massive digital systems. Since technologies are optimized with these digital systems in mind, designers will have to make do with standard CMOS processes in the years to come. We address analog filter design from this perspective. Filters form important blocks in applications ranging from computer disc-drive chips to radio transceivers. In this book, we develop the theory and techniques necessary for the implementation of high frequency (hundreds of megahertz) programmable continuous time filters in standard CMOS processes. Since high density poly-poly capacitors are not available in these technologies, alternative capacitor structures have to be found. Met- metal capacitors have low specific capacitance. An alternative is to use the (inherently nonlinear) capacitance formed by MOSFET gates. In Chapter 2, we focus on the use of MOS capacitors as integrating elements. A physics-based model which predicts distortion accurately is presented for a two-terminal MOS structure in accumulation. Distortion in these capacitors as a function of signal swing and bias voltage is computed. Chapter 3 reviews continuous-time filter architectures in the light of bias-dependent integrating capacitors. We also discuss the merits and demerits of various CMOS transconductance elements. The problems encountered in designing high frequency programmable filters are discussed in detail.

✦ Table of Contents

Introduction....Pages 1-4
Mos Capacitors: Modeling & Potential as Integrating Elements in Continuous Time Filters....Pages 5-32
A Review of Integrator Architectures....Pages 33-69
Time Scaling in Electrical Networks....Pages 71-94
Filter Design....Pages 95-132
Filter Testing and Measured Results....Pages 133-147
Applications of Scaling to Other Filter Techniques....Pages 149-163
Tuning in Continuous-time Filters....Pages 165-190

✦ Subjects

Circuits and Systems; Electronic and Computer Engineering