Some Comparisons Between FIR and IIR Digital Fibers

Some Comparisons Between FIR and IIR Digital Filters By L. R. RABINER, J. F. KAISER, O. HERRMANN, and M. T. DOLAN (Manuscript r e c e i v e d July 27, 1973) The purpose of this paper is to make comparisons between optimum, linear phase, finite impulse response (FIR) digital filters and infinite impulse response (IIR) digital filters which meet equivalent frequency domain specifications. The basis of comparison is, for the most part, the number of multiplications per sample required in the usual realizar tions of these filters--i.e., the cascade form for IIR filters, and the direct form for FIR filters. Comparisons are also made between group-delay equalized filters and linear phase FIR filters. Considerations dealing with finite ivord-length effects are discussed for both these filter types. A set of design charts is also presented for determining the minimum filter order required to meet given loiv-pass filter specifications for both digital and analog filters.