Efficient technique for improving the frequency response of CIC decimation filter

CIC (cascaded-integrator-comb) filter is widely used as the decimation filter in oversampled sigma-delta analog-to-digital converter (ADC) due to its simplicity which requires no multiplication or coefficient storage. However, the frequency response of the CIC filter has a high passband droop and low stopband attenuation. In this paper we present two-stage structure based on CIC and cosine filters which is multiplier-free. Besides the proposed filter does not have any filtering at the high input rate and exhibits the high attenuation at the frequency point of interest.