Note 49. Designing IIR Filters: Background and Options

The block diagram in Figure 49.1 represents the direct form implementation for an infinite impulse response (IIR) digital filter. The filter consists of an all-zero section followed by an all-pole section. At time n, the all-zero section computes a weighted sum of the inputs from times nM through n. To this result, the all-pole section adds a weighted sum of the previous outputs from times nN through n – 1. The usual mathematical characterizations for an IIR filter are summarized in Math Boxes 49.1 and 49.2.

Figure 49.1. Block diagram for IIR filter

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The difference equation for the ...

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