A Class of Infinite-Duration Impulse Digital Filters for Sampling Rate R
Hernán Martínez · 1979
A new class of recursive digital filters for sampling rate reduction is discussed. These fiiters present equiripple behavior in the magnitude response, with all their zeros located on the unit circle. These new fiiters bring together, to some extent, the advantages of finiteduration im ulse response (FIR) and elliptic designs by having only powers of zg in the denominator (D is the decimation ratio). Only every Dth output has to be computed, as in the FIR case; while some feedback terms, as in the elliptic case, are ais0 present. The design and some optimality properties of these fiiters are discussed. Some characteristics of filters with only powers of zD in the denomi- nator, such as polezero location, group delay, and coefficient sensi- tivity are discussed and compared with elliptic designs. It is shown how these new fiiters require significantly fewer multiplications per second than equivalent FIR and elliptic designs.