CIC Decimation Filters Based on Polyphase Structure and Partially Sharpening Technique
Li Bing①②; Zheng Jin①; Ge Lin-dong①
①Institute of Information Engineering, Information Engineering University, Zhengzhou 450002, China; ②Electromagnetism and Frequency Spectrum Management Center of PLA General Staff Headquarters, Beijing 100078, China
Abstract：In this paper an improved solution to the design of Cascaded-Integrator-Comb (CIC) filter is proposed, in which the overall transfer function is factorized to recursive and non-recursive parts. The cascade factors of two parts can be adjusted independently. The sharpening is applied to recursive part to correct the passband droop, and decimation factor is moved prior to the sharpening of recursive part by the use of equivalent transform to operate at a low rate. Polyphase decomposition is applied to non-recursive part to realize high-speed filtering. Computer simulation shows that the modified CIC filter has a frequency response comparable to that of sharpening CIC filters while design flexibility is increased. The effect of the cascade factor of recursive and non-recursive parts on the modified CIC frequency response is discussed in terms of passband droop and alias rejection.
2007, Vol. 29 
