Optimal Sharpening of Compensated Comb Decimation Filters: Analysis and Design

David Ernesto Troncoso Romero,Gordana Jovanovic Dolecek,Massimiliano Laddomada

doi:10.1155/2014/950860

David Ernesto Troncoso Romero, Gordana Jovanovic Dolecek + Show 1 more

Open Access

https://doi.org/10.1155/2014/950860

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Abstract

Comb filters are a class of low-complexity filters especially useful for multistage decimation processes. However, the magnitude response of comb filters presents a droop in the passband region and low stopband attenuation, which is undesirable in many applications. In this work, it is shown that, for stringent magnitude specifications, sharpening compensated comb filters requires a lower-degree sharpening polynomial compared to sharpening comb filters without compensation, resulting in a solution with lower computational complexity. Using a simple three-addition compensator and an optimization-based derivation of sharpening polynomials, we introduce an effective low-complexity filtering scheme. Design examples are presented in order to show the performance improvement in terms of passband distortion and selectivity compared to other methods based on the traditional Kaiser-Hamming sharpening and the Chebyshev sharpening techniques recently introduced in the literature.

Highlights

IntroductionEfficient decimation filtering for oversampled discrete-time signals is key in the development of low-power hardware platforms for reconfigurable communication transceivers [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26]
(b) We introduce a low-complexity structure in which the simple multiplierless compensator can be embedded into the cascaded chain of comb filters working at lower rate
The following examples are discussed to show the improvement of magnitude characteristics of comb filters achieved with the proposed method in comparison to other sharpening-based schemes recently introduced in the literature

Summary

Introduction

Efficient decimation filtering for oversampled discrete-time signals is key in the development of low-power hardware platforms for reconfigurable communication transceivers [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26]. From a practical point of view, decimation is usually accomplished using a cascade of two (or more) stages. The filter in the first stage is a comb filter of order K decimating by a factor M, with z-transfer function and zero-phase frequency response, respectively, given as HK (z) = ( 1 M 1 − z−M 1 − z−1 K ), (1) HK (ω) = ( sin (ωM/2) )

Methods

Discussion

Conclusion