Non-recursive decimation filters with arbitrary integer decimation factors

Abstract

Cascaded integrator comb (CIC) filters are in wide use in oversampled analog-to-digital converters. In this study, the authors advances three new cascaded decimator structures with integer coefficients designed using a polynomial factorisation approach. Each one of the designed decimators shows better stopband attenuation for a given order and decimation factor than the CIC or recently proposed generalised comb filter (GCF) and may not require any prefilter for performance enhancement. A fourth new decimator structure is a hybrid between the CIC and GCF with coefficients approximated by integers. Decimator power dissipation analysis and optimisation have previously been done either by counting the number of additions per sample rate or by focusing on register clock distribution. The authors propose a new metric for estimating the power dissipation of a filter structure from its architecture accounting for dissipation both in the adder cells and the flip-flops. The authors show frequency domain characteristics and compare power dissipations of all the new structures using a representative example.