Improving alias rejection in comb decimation filters for odd decimation factors
Gordana Jovanović Doleček, Jose De Jesus Carmona Suarez · 2017
This paper presents a two-stage comb decimation filter for odd decimation factors, which are factors of three. The first stage is a comb decimated by M/3, (M is the overall decimation factor), while the second stage is a comb, decimated by three. The aliasing rejection is improved by cascading a simple multiplierless filter in the second stage. As a consequence, the aliasing rejection is improved in all folding bands except for the third, sixth, ninth, etc. Mathematical background for the choice of the filter in the second stage is provided. The comb filters in both stages can be implemented either in recursive or nonrecursive forms. The comparisons with some methods, recently proposed in literature show the benefit of the proposed method.