For many applications, the FIR and digital filter (IIR) can be used interchangeably. However, they do have a few key differences:
- FIR filters have a linear phase response. They create minimal signal distortions in the time domain.
- IIR filters are computationally inexpensive compared to FIR filters. The propagation delay is typically shorter.
- FIR filters can easily create very steep cut-off corners, where the slopes of IIR filters are less tunable.
- IIR filters have analog counterparts. You can use the IIR filter to simulate analog filters or the other way around. FIR filter can only be implemented digitally.