Improving Aliasing Rejection by Inserting Additional Zeros into Folding Bands Using Simple Filters

This paper presents a novel multiplierless two-stage comb-based decimation filter with an improved aliasing rejection, in comparison with the original comb filter. This is achieved by inserting additional zeros into comb folding bands provided by additional comb filters of different lengths in the second stage, and the cascaded modified combs in the first stage. The parameters of design are the same as in two-stage comb, i.e. the decimation factors of the first and second stages and the order of comb. The efficient structures are also discussed. Finally, the comparisons with the methods from literature are presented. The proposed method is convenient for the decimation factors which can be presented as a product of two integers.