Modified CIC filter for rational sample rate conversion

Abstract

The modification of the conventional CIC (cascaded-integrator-comb) filter for rational sample rate conversion (SRC) in software radio (SWR) systems is presented here. The conversion factor is a ratio of two mutually prime numbers, where the decimation factor M can be expressed as a product of two integers. The overall filter realization is based on a stepped triangular form of the CIC impulse response, the corresponding expanded cosine filter, and sine-based compensation filter. This filter performs sampling rate conversion efficiently by using only additions/subtractions making it attractive for software radio (SWR) applications.