Cascade Structure of Narrow Equiripple Bandpass FIR Filters

This brief introduces a novel closed-form method for a robust evaluation of partial impulse responses in a cascade structure of narrow equiripple (ER) bandpass finite-impulse-response filters. The approach presented here is based on a generating polynomial for an ER approximation. The importance of the method is seen in its inherent robustness, which significantly outperforms the existing numerical approach. Consequently, much longer filters can be represented in their cascade form. Two examples demonstrate the functionality, performance, and usefulness of the method, as well as its superiority in terms of robustness over the existing approach.