A ripple reduction technique for digital filters

Author

Powell, Scott R. ; Temes, Gabor ; Chau, Paul M.

Author_Institution

Dept. of Electr. & Comput. Eng., California Univ., San Diego, CA, USA

fYear

1991

fDate

11-14 Jun 1991

Firstpage

268

Abstract

A post-filtering technique is proposed for reducing the frequency domain error (ripple) of FIR (finite impulse response) and FFT (fast Fourier transform) based digital filters. The post-filter is of low complexity and acts to cancel the frequency ripple of the main filter. By assuming that the frequency ripple of the main filter is approximately sinusoidal, the post-filter can be constructed from a single shift-adder and unit delays. This post-filter resembles a simple echo canceller and typically reduces the passband ripple (in dB) of optimum digital filters by a factor of 2-6. The reduced passband ripple permits lower-order filters to be used with more weight given towards increasing the stopband attenuation or narrowing the transition bandwidth

Keywords

digital filters; echo suppression; fast Fourier transforms; filtering and prediction theory; signal processing; FFT based filters; FIR based-filters; digital filters; echo canceller; fast Fourier transform; finite impulse response; frequency domain error; frequency ripple; post-filtering technique; ripple reduction technique; shift-adder; unit delays; Attenuation; Band pass filters; Bandwidth; Delay; Digital filters; Echo cancellers; Fast Fourier transforms; Finite impulse response filter; Frequency domain analysis; Passband;

fLanguage

English

Publisher

ieee

Conference_Titel

Circuits and Systems, 1991., IEEE International Sympoisum on

Print_ISBN

0-7803-0050-5

Type

conf

DOI

10.1109/ISCAS.1991.176325

Filename

176325