Cascading Sharpened CIC and Polyphase FIR Filter for Decimation Filter

This paper is concerned with design of cascading CIC filter and FIR filter to improve the passband droop and stopband attenuation for decimation filter. Decimation filter has wide application in both analog and digital systems for data rate conversion as well as filtering. We have three class of filters FIR, IIR and CIC filters. IIR filters are simpler in structure, but not satisfy linear phase filter requirements, which are required for time sensitive features like video and speech. CIC filter don’t have this drawback, they are coefficient less, hardware requirement is much reduced, but as they don’t have well defined frequency response. So another structure is proposed which takes advantage of good features of both CIC and FIR filter structures. Hence in this paper concerned about cascading sharpened CIC filter and polyphase structure of FIR for efficient compensation in decimation is designed, which has better passband and stopband performance. Keywords— Multirate filtering, CIC, Compensation Technique, Polyphase structure, FIR