A new approach to designing computationally efficient interpolated FIR filters
More efficient use of multipliers in FIR filters can be achieved at the expense of a slight increase in delay by designing sparse filter structures. We have developed a new, relatively simple approach to designing sparse cascaded filters, also described in the literature as interpolated FIR filters. Our method is heuristic in nature, but gives surprisingly good results without requiring iterative design or investigation of a large number of alternative parameterizations. The design uses the efficient and widely available Remez exchange algorithm along with some routines that we have written for Matlab. Although the resulting designs are not optimal in a minimax-error sense, they have reduced RMS error, which may be attractive for some applications. We give design examples, and study the effects of coefficient quantization.