Design of FIR Filters Using Identical Subfilters of Even Length

This article presents an analytic development for the design of linear-phase FIR digital filters with reduced computational and hardware complexity. The proposed approach is based on a frequency transformation implemented by replacing a subfilter in a prototype filter. The previous approach forced subfilters and prototype filters to be of odd length, while this approach supports subfilters and prototype filters of even length. Depending on the specifications of the filter, either the previous method or our proposed method can give the optimal solution for the design of the required filter. It has been shown by means of an example that the overall composite FIR filter with the proposed approach contributes to a saving of 22%, 22% and 22% in the number of adders, delays and multipliers respectively compared to the previous approach.