A novel switched capacitor frequency tuning technique for continuous-time Gm-C filters

Abstract

A novel approach for the automatic frequency tuning of Continuous Time Filters is presented. This approach is based on a switched capacitor circuit and only needs three capacitors, some switches and a replica transconductor to adjust the pole frequency of the filter. Despite the simplicity of the scheme, the accuracy of the proposed system is under 1% of frequency error. To evaluate the idea a version of the circuit has been designed in a 0.5 µm CMOS technology with a 3.3 V power supply and simulation results are provided.