Novel Two-Stage Comb Decimator

A simple method for the design of a multiplier-less comb-based decimation filter is presented. The filter compensates the comb passband droop, and has the desired attenuation in the first folding band. The proposed structure has two decimation stages, both with simpler comb filters. The desired attenuation in the first folding band is achieved by an appropriate number of cascaded combs in the second stage. A simple compensation filter, working at a low output rate, provides the desired compensation in the pass band. The choice of the design parameters is presented along with a comparison of the proposed method to some other existing design methods.