Infinite Impulse Response Filters
Donald S. Reay · 2015
This chapter focuses on infinite impulse response (IIR) filters that, typically, make use of the vast knowledge that exists concerning analog filters. The design procedure described in this chapter involves the conversion of an analog filter into an equivalent discrete filter. Either the impulse invariance or bilinear transformation (BLT) technique may be used to effect that conversion. Several different structures may be used to represent an IIR filter: direct form I structure, direct form II structure, and direct form II transpose. The impulse variance method of IIR filter design is based on the concept of mapping each s-plane pole of a continuous-time filter to a corresponding z-plane pole. The BLT is the most commonly used technique for transforming an analog filter into a digital filter. It provides one-to-one mapping from the analog s-plane to the digital z-plane. The chapter provides several examples that illustrate the implementation of IIR filtering.