A New Two-Stage CIC-Based Decimation Filter

This paper presents a new two-stage CIC-based decimation filter for input signals occupying 3A of the digital band. The decimation factor M is assumed to be an even number. The decimation factor of the first stage is M/2, whereas, that of the second stage is 2. A sine-based compensation filter is introduced to decrease the passband droop of the CIC filter and a cosine filter is introduced to improve the overall stop-band characteristic. As a result the SNR {signal-to-noise ratio) is improved. Using the polyphase decomposition of the comb filters, the polyphase components of the comb filters are moved to the lower rate which is M/2 less than the input rate. Consequently there is no filtering at the high input rate. The proposed filter performs decimation efficiently using only additions/subtractions making it attractive for software radio (SWR) applications.