A cascade connection of a continuous-time filter and a peaking N-path filter

摘要

A peaking transferred impedance filter (TIF) circuit is placed in series with a continuous time filter (110, figure 1) to compensate the falling amplitude response of the continuous time filter near a band edge or a zero. The continuous time filter stop band may be designed to reject a blocking signal such as transmit signal leakage. The TIF circuit comprises a splitter 210, an N-path bandpass filter 220, scalers 230 and 240, and a combiner 250. The scaling and combining circuits may be merged (figure 6), the scaling factors C1 and C2 being effected by choice of relative transistor sizes. Equalization of the passband response by the TIF filter allows the continuous time filter to be adapted to give higher rejection response of an unwanted signal. Fewer continuous-time filter stages are required to achieve a desired passband flatness and stopband rejection response.