Design of comb-based decimation filter with low power consumption, increased alias rejection and decreased passband droop

Abstract

This paper presents design of a low power comb-based decimation filter for decimation of 100. The proposed structure is composed of two stages. The first and second stages are decimated by 4 and 25, respectively. The first stage is a non-recursive structure composed of two cosine filters each decimated by 2. The second stage is a Cascaded-Integrator-Comb (CIC) structure, decimated by 25. Since CIC structure is moved to lower rate, we get a low power structure. The alias rejection is improved increasing the number of cascaded filters by 1 or 2, at second stage. The passband droop is decreased by introducing the compensator at lower rate, i.e. after downsampling by 100. The parameters of compensator are obtained using method of intervals.