High-speed multiplierless Frequency Response Masking (FRM) FIR filters with reduced usage of hardware resources

This paper addresses the design of Frequency Response Masking (FRM)-based Finite Impulse Response (FIR) filters with high speed and reduced usage of hardware resources. In this proposal, the model subfilter is implemented using a hybrid quasi-direct structure that allows reducing the critical path while simultaneously saves silicon area by sharing a long delay line with the model´s complementary pair. The subfilters are made multiplierless by expressing their coefficients in a Minimal Signed Digit representation. Then a simple Common Subexpression Elimination heuristic that takes advantage of the hybrid structure is introduced. As a result, filters designed with the proposed method preserve both, a low usage of hardware resources similar to FRM-based methods with model and complementary filters implemented in direct form, and a high speed characteristic similar to FRM-based methods with model and complementary filters implemented in transposed form.