Improving IIR Filter Design by Considering the Allocation and Locations of Poles and Zeros

The effects of the distribution and the location of the poles and zeros of recursive (IIR) digital filters are investigated. This paper first investigates the distribution of non-trivial poles and zeros and we demonstrate that we can, for example, design a digital filter that both out-performs an elliptic digital filter and has a lower computational cost. In the second part of the paper, we consider the design of recursive filters having nearly-linear phase in the passband to see how constraining pole radius facilitates achieving lower overall group delay.