Comparison of FIR and IIR filters

The non-recursive FIR filter has a finite memory due to the finite number of delays that can be realized in a practical implementation. FIR filters usually have superior phase characteristics. To obtain sharp cut-off characteristics, FIR filters need to be of high order.

On the other hand, a recursive IIR filter has infinite memory due to its dependence on all prior outputs. Moreover, it generally requires a significantly lower number of elements to obtain a specific cut-off characteristic. The phase characteristics of IIR filter, however, are inferior to those of FIR filters.