A Method to Derate the Rate-Dependency in the Pass-Band Droop of Comb Decimators

TL;DR

This paper introduces a method to reduce the rate-dependency of pass-band droop in comb decimators by cascading a symmetric 3-tap FIR filter, applicable to various decimator designs.

Contribution

It proposes a simple, general derating technique using a symmetric FIR filter to mitigate pass-band droop in comb decimators, independent of specific designs.

Findings

Effective reduction of pass-band droop rate-dependency.

Compatible with existing comb decimator and droop-compensation designs.

Simple implementation with fixed coefficients based on order N.

Abstract

This paper presents a method to derate the dependency on the decimation factor, $M$, of the pass-band droop inherent to $N$-th ordered comb decimators. It is achieved by cascading a symmetric 3-tap FIR filter in the integral stage of the corresponding comb decimator and choosing the coefficients only as a function of order $N$. The proposed derating method derived from the conventional comb decimator can be readily applied to any recently developed comb decimator and droop-compensation filter design method.