Design of a Chebyshev low pass filter with automatic frequency calibration

Abstract

A 6th order Chebyshev type I low pass filter applied in zero-IF wireless receivers, implemented in 0.18 µm CMOS technology is introduced, this filter is realized with leapfrog structure, has an attenuation of 30dB at 5.25MHz, less than 1dB in-band ripple, 25nV/sqrt(Hz) input referred noise at 5 kHz, and draws 2.6mA from 1.8V supply. By employing frequency calibration circuit, the cut-off frequency of the filter can be tuned to within 4% from the desired value, which is 3.756 MHz.