Decimating digital finite impulse response filter

Abstract

A decimation type digital filter which utilizes the thinned-out signal of a finite impulse response (FIR) filter having N taps for processing the signal by the product sum operation of filter coefficients and the input signals inputted at every first period, in which, on the basis of the ratio K between a first period which is the input signal period and an output signal period and the number of taps N, M (a value obtained by raising below the decimal point of N/K) registers are provided and M successive output signals are processed by the product sum operation in parallel by respective registers, whereby the input signal is not necessarily to be held, a capacity of the register may be minimized and processing may be effected once for each register during the first period or by M number of times of product sum operation in total, thus the operating speed can be reduced to 1/K and the capacity and the operating speed can be optimized.