Embedded Signal Processing with the Micro Signal Architecture

Chapter 4

Digital Filtering

As discussed in Chapters 2 and 3, a filter can be designed to alter the spectral content of input signals in a specified manner to achieve the desired objectives, and digital filtering is widely used for embedded systems. This chapter introduces the design, analysis, application, and implementation of time-invariant FIR and IIR filters and time-varying adaptive filters.

4.1    INTRODUCTION

As discussed in Section 3.2.3, digital filters can be divided into two categories: FIR filters and IIR filters. These filters can be represented by difference (or I/O) equations, system transfer functions, and signal flow diagrams. The I/O equations of FIR and IIR filters are defined in Equations 2.3.4 and 3.2.12, the transfer functions are defined in Equations 3.2.7 and 3.2.13, and the signal flow diagrams are illustrated in Figure 2.16 and Figure 3.3, respectively.

The process of deriving the digital filter transfer function H(z) that satisfies a given specification is called digital filter design. Although some applications require only simple filters such as the moving-average, notch, and peaking filters introduced in Chapters 2 and 3, the design of more sophisticated filters requires the use of more advanced techniques. A number of computer-aided design tools (such as MATLAB) are available for designing digital filters. In this chapter, we focus on using the Filter Design and Analysis Tool (FDATool) for designing FIR and IIR filters in Sections 4.2 and 4.3, respectively. ...