Analog Integrated Circuit Design, 2nd Edition

A basic understanding of discrete-time signal processing is essential in the design of most modern analog systems. For example, discrete-time signal processing is heavily used in the design and analysis of oversampling analog-to-digital (A/D) and digital-to-analog (D/A) converters used in digital audio, wireless communication, and instrumentation applications. Also, a discrete-time filtering technique known as switched-capacitor filtering is a popular approach for realizing fully integrated analog filters. Switched-capacitor filters are in the class of analog filters since voltage levels in these filters remain continuous. In other words, switched-capacitor filters operate and are analyzed using discrete time-steps but involve no A/D or D/A converters; hence, they are quantized in time but not in amplitude. This chapter presents some basic concepts of discrete-time signals and filters.

13.1 OVERVIEW OF SOME SIGNAL SPECTRA

Consider the spectra of sampled and continuous-time signals in the block diagram systems shown in Fig. 13.1, where it is assumed that the continuous-time signal, xc(t), is band limited through the use of an anti-aliasing filter (not shown). DSP refers to Discrete-time signal processing, which may be accomplished using fully digital processing or discrete-time analog circuits such as switched-capacitor filters. Some example time signals and frequency spectra for ...