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This study is concerned with the problem of designing computationally efficient generalised comb (GC) filters. Basically, GC filters are anti-aliasing filters that guarantee superior performance in terms of selectivity and quantisation noise rejection compared to classical comb filters, when used as decimation filters in multistage architectures. Upon employing a partial polyphase (PP) architecture proposed in a companion study, the authors develop a sensitivity analysis in order to investigate the effects of the coefficients' quantisation on the frequency response of the designed filters. The authors show that the sensitivity of the filter response to errors in the coefficients is dependent on the particular split of the decimation factor between the two sub-filters constituting the PP architecture. The sensitivity analysis is then used for developing a fixed-point implementation of a sample filter from the class of GC filters, used as reference filter throughout the study. Finally, the authors present computer simulations in order to evaluate the performance of the designed fixed-point filters. [ABSTRACT FROM AUTHOR]

Cascaded-integrator-comb (CIC) filters are efficient anti-aliasing rate-conversion filters widely used for ΣΔ AID converters. High-order structures, attempting to increase the noise rejection within the folding bands, have the drawback of inserting multiple zeros in the same positions and increasing the edge-band attenuation. A combination of sharpened and CIC filters is proposed in the paper, with the goal of increasing the rejection of the LA quantisation noise around the folding bands and reducing the pass-band drop of the designed decimation filters with respect to classic CIC structures. Design criteria, leading to optimised structures, and comparisons are given with respect to both classical and modified CIC filters. [ABSTRACT FROM AUTHOR]