Chapter 8

Infinite Impulse Response (IIR) Filters


The chapter introduces the infinite impulse response (IIR) filter. Infinite impulse response (IIR) filters are based on analog filters, where the frequency response is defined by both poles and zeros. Finite impulse response filters, in contrast, only have zeros. The presence of poles in the IIR filter causes the impulse response to be infinitely long. Poles are generated using feedback, which can also cause numerical instability. Despite these complications, IIR filters can be useful because for an equivalent frequency response, IIR filters require far fewer multipliers to implement. The process of designing an IIR filter is to start with an analog filter, and then map into the digital ...

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