IIR Digital Filter Design

Filtering is an important aspect of signal processing. It allows desired frequency components of a signal to pass through the system without distortion and suppresses the undesired frequency components. One of the most important steps in the design of a digital filter is to obtain a realizable transfer function H(z), satisfying the given frequency response specifications. In the case of the design of an IIR filter, it is required to confirm that H(z) is stable. The most common technique used in designing IIR digital filters involves first designing an analog prototype lowpass filter and then transforming the prototype to a digital filter. In this chapter, the design of analog lowpass filters is first described. Second, frequency transformations for transforming analog lowpass filter into bandpass, bandstop, or highpass analog filters are considered.