Efficient implementation of sharpened CIC decimation filters for software radio receivers

We propose an efficient structure for sharpened, cascaded integrator comb (CIC) based, decimation filter. Novelty of proposed structure is that it can be achieved for any decimation factor and its efficient finite impulse response (FIR) implementation form. It consists of multirate cascade of sharpened CIC filters with lower (prime) decimation factors. Every cascade stage can be implemented in nonrecursive FIR form with sharpened higher order Comb filters as building blocks. Applying polyphase decomposition, every stage can work on lower decimation rate depending of decimation factor of that stage. Additionally, due to special pole structure of filter stages in cascade, first few stages can be implemented with reduction in system order, depending of stage position and decimation ratio.