Programmable IIR filter using bitstream processing

Abstract

This paper presents a compact CMOS realization of cascaded biquad digital filters using 2nd order /spl Delta//spl Sigma/ modulators requiring no multibit multiplier. A bitstream biquad is derived with just one /spl Delta//spl Sigma/ modulator for each pair of poles which leads to a very compact implementation. No significant degradation of sensitivity nor of dynamic range is observed. The analog interfaces are highly simplified due to the bitstream input and output formats.