0.18μ CMOS Gm-C digitally tuned filter for telecom receivers

The design of widely programmable low-pass second order G_m-C filter for telecom applications is presented. A digital tuning scheme is proposed for getting a frequency programmability range from 1 MHz to 40 MHz compensating the technological spread. The digital tuning circuitry can be turned off during signal processing. A 0.18 μm CMOS technology with a 1.8V power supply has been used for the filter design. A 62dB constant dynamic range is obtained for the filter programmability range by switching input transistors sizes and bias currents of each OTA of the filter.