On simple comb zero rotation: Rouche’s theorem approach
Jose Ricardo Garcia Baez, Gordana Jovanović Doleček · International Journal of Electronics · 2016
This paper presents the method for increased attenuation in comb-folding bands by using a simple comb zero rotation on the unit circle in the complex z-plane. The rotations of the zeros of the comb filter on the unit circle are achieved by adding and subtracting a positive constant to a comb-system function. Even and odd parities of the length (or decimation factor) of the comb filter are discussed separately. The resulting filter is a multiplierless, linear-phase filter with the increased widths of the comb-folding bands relative to the original comb filter. Efficient structures and the discussion how to choose the parameters of design are also provided. Finally, the comparisons, with some existing methods based on comb rotation, are also included.