Improved Method for Wideband CIC Decimation Filters

The decimation filters of better performance is demanded in multi-rate process when wideband signal with high sample rate is processed by digital IF receiver. The frequency response of classic CIC decimation filters does not meet the requirement when it process wideband signal. The problem is that it has to increase pass-band attenuation to achieve the necessary stop-band attenuation with poor alias rejection. For solving the problem, the paper proposes an improved method which improves alias rejection by taking advantage of sharpening technique on the two-stage comb filter, and applies compensator filters in low sample rate with low computation to improve pass-band characteristics. The simulation result indicates that pass-band attenuation of proposed filter is over than -0.002dB, stop-band attenuation is less than -57dB, and anti-aliasing performance is better.