Design of Chebyshev Comb Filter (CCF)-based decimators with compensated passband

Chebyshev Comb Filters (CCFs) are a novel class of low-complexity filters recently introduced in literature, especially useful in multi-stage decimation processes. However, the magnitude response of CCFs presents in the passband region an undesirable droop that increases as the order of the filter increases. In this paper we introduce the design of low-complexity second-order compensators to improve the passband characteristic of CCFs. The proposed compensation filters are designed using the amplitude transformation method recently presented in literature to design traditional comb compensators. A simple formula to obtain the coefficients of the compensator is provided, thus the design becomes straightforward. It is shown by means of a detailed example that the proposed cascaded CCF-compensator has a lower computational complexity comparing to traditional cascaded comb-compensator.