Active low-pass filter design with variable filter order for wideband transceivers

Modern wideband transceivers that supports several different wireless communication standards require flexible intermediate frequency (IF) chains. Active low-pass filters are essential blocks in all transceiver architectures and their IF chain designs. In this paper, an active low-pass filter with a variable filter order and cut-off frequency is proposed. The filter order control gives a possibility to optimize the IF chain for different modes of transceiver operation like reduced power consumption or/and noise. The proposed filter can achieve a 6th, 4th or 2nd order low-pass filter response with a tunable cut-off frequency from 20MHz to 120MHz. The proposed design was verified with Cadence using a 65nm CMOS technology.