Notes on Digital Signal Processing: Practical Recipes for Design, Analysis and Implementation

Note 33. Linear-Phase FIR Filters

One of the advantages that FIR filters have over IIR filters is that it is relatively easy to design FIR filters that have constant group delay across all frequencies. Constant group delay is a desireable property for a filter to have because it means that a signal passing through the filter does not experience any delay distortion due to different frequency components being delayed by different amounts. Linear-phase FIR filters are conventionally separated into four types depending upon the four combinations of odd-even filter length and odd-even symmetry in the filter’s impulse response. This note examines these four types of linear-phase FIR filters and their properties.

When a filter has constant group delay ...