Patent ID: 6750793
Filing Date: 2004-06-15
Classification: H03H

Abstract:
A decimation filter for use in A/D conversion, comprising:a plurality of FIR filters configured in a cascade connection, each for conducting down sampling, wherein a coefficient word length of a last-stage FIR filter is shorter than a coefficient word length which enables desirable attenuation in an inhibition zone of the last-stage FIR filter, such that there is caused a region where attenuation is insufficient in an inhibition region of the last-stage FIR filter, a coefficient of the last-stage FIR filter is determined such that the region where attenuation is insufficient is focused in the vicinity of a Nyquist frequency, and a FIR filter immediately before the last-stage FIR filter is arranged so as to attenuate the Nyquist frequency of the last-stage FIR filter.