Use of comb filters for efficient VLSI implementation of reduced clock frequency noise shapers

The use of comb filters as an elegant means of reduced clock frequency noise-shaping without excessive hardware overhead is presented. The significance of the method is illustrated using second order noise-shaping characteristics. A 256 times oversampled and noise-shaped bit-stream sequence is obtained by running a second order noise shaper at a clock frequency four times lower than that of the bit-stream sampling rate, in association with an in-loop multi-bit to four single bit transformation at a tolerable hardware overhead