A 1V active RC filter with on-chip frequency and Q tuning

A 1V 1MHz second-order continuous-time active RC filter with on-chip automatic tuning fabricated in a conventional 1.2µm CMOS process is presented. Low voltage filter is designed by adding current sources to the opamp inputs. A Q tuning technique that does not require peak detectors is proposed for tuning low voltage active RC filters. For a 5kHz input signal, the filter achieves a THD of -60.2dB for a peak-to-peak output voltage of 600mV. The frequency tuning range is between 585kHz and 1.25MHz. The entire system consumes less than 2.5mW for a supply voltage of ±0.5V.