A systematic technique for designing highly selective multiplier-free FIR filters

A systematic technique is introduced for designing multiplier-free FIR (finite impulse response) filters. This technique is based on the use of identical copies of the same subfilter which are interconnected with the aid of a few additional adders and tap coefficients. In the proposed approach, the additional tap coefficients are first quantized in a systematic way to values which are simple combinations of powers-of-two. The second step is then to design the subfilter in such a way that its coefficients have similar simple representation forms. This can be done without time-consuming optimization since the ripple values and the allowable quantization errors for the subfilter are huge compared to those of the overall filter. Even direct rounding can be used to arrive at the desired result