A NOVEL DCT-BASED PREFILTER STRUCTURE FOR EFFICIENT DIGITAL-FILTER DESIGN

In this paper, we present a novel prefilter structure for FIR digital filter design based on the recursive discrete cosine transform (RDCT) filter bank. The proposed prefilter structure is suitable for designin g the lowpass, bandpass and highpass digital filters simultaneously. I n the lowpass case, the proposed prefilter structure can be simplified to the recursive running sum (RRS) section. In the bandpass and highp ass cases, implementing the new prefilter only needs two multipliers a nd five adders regardless of the filter length and center frequency. C ompared with the conventional equiripple design approach, the proposed prefilter-equalizer cascade exhibits approximately the same sensitivi ty to coefficient quantization. In addition, the new structure can red uce the roundoff noise and provide significant savings in the number o f multipliers and adders at the expense of slightly larger filter leng th.