Efficient Prefiltering for FIR Digital Filters

This paper presents three types of prefiltering for FIR digital filters to decrease the number of multipliers required. The first type is based on cyclotomic polynomials. It can be applied to any types of band-selective filters. The second is a mirror-image quadratic polynomial to make a passband shaping. Both types of the prefilters are used with the interpolation technique, and this improves each primitive characteristic in terms of the sharp transition. In the prefilter-equalizer design approach, these prefilterings bring about the reduction of the number of multipliers required in hardware implementation. The prefiltering efficiency is demonstrated by a few examples