Modified comb decimation filter: Design and implementation
Ricardo Garcia Baez, Gordana Jovanović Doleček · 2016
This paper presents a novel simple method to improve the alias rejection of a comb decimation filter by adding and subtracting a positive constant to the comb filter coefficients. The constant is chosen in a way that the resulting filter is a multiplierless filter and that the zeros of the modified comb transfer function remain on the unit circle in the vicinity of the corresponding original comb zeros. The positions of zeros result in wider folding bands leading to the improvement of the modified comb alias rejections in folding bands. This modified comb is suitable for the implementation using a special structure that requires shifts and only two adders. FPGA implementation confirms the efficiency of the proposed design.