Analog MOS Integrated Circuits for Signal Processing

Chapter Six

NONFILTERING APPLICATIONS OF SWITCHED-CAPACITOR CIRCUITS

Although analog filtering applications received the most attention recently among switched-capacitor circuits, there are many other analog signal processing and generation tasks which can be performed using the same fabrication technology and circuit elements as those used in the filters. In this chapter, some simple circuits are discussed which can be applied to carry out such nonfiltering analog signal processing functions. These include voltage amplifiers, digital-to-analog (D/A) as well as analog-to-digital (A/D) converters, voltage comparators, modulators, rectifiers and peak detectors, as well as relaxation and sine-wave oscillators. No attempt was made to include all available circuits, or even all possible areas of applications. Nor did we try to give an in-depth description of such important topics as A/D and D/A signal conversion. Rather, we attempted merely to illustrate the versatility of switched-capacitor circuits, and show how the MOS technology and devices originally developed for digital logic circuits can be utilized to perform such entirely different tasks.

Naturally, in most applications it is advantageous to fabricate the largest possible number of system building blocks on the same chip. Hence, it is to be expected that many more signal processing functions, currently performed by discrete ...