Chapter 32

Implementing Digital Filters in VHDL

Peter Wilson

32.1 Introduction

An important part of systems that interface to the “real world” is the ability to process sampled data in the digital domain. This is often called sampled-data systems (SDS) or operating in the Z-domain. Most engineers are familiar with the operation of filters in the Laplace or S-domain where a continuous function defines the characteristics of the filter and this is the digital domain equivalent to that.

For example, consider a simple RC circuit in the analog domain as shown in Figure 32.1. This is a low-pass filter function and can be represented using the Laplace notation shown in Figure 32.1

Figure 32.1 RC filter in the analog domain

This has the equivalent S-domain ...

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