Fully integrated active RC filters in MOS technology

A fully integrated continuous-time low-pass filter has been fabricated with CMOS technology. The device implements an active RC network using integrated capacitors and MOS transistors operated in the nonsaturation region as voltage-controlled resistors. The filter topology is fully balanced for good linearity and for good power supply rejection. The cutoff frequency is voltage adjustable around 3 kHz, allowing compensation for process and temperature variations. For 5-V power supplies a dynamic range of over 94 dB has been achieved.