A 1.5-V supply, video range frequency, Gm-C filter

A 1.5 V single supply, fourth order lowpass Butterworth Gm-C filter, on a 0.6 μm standard CMOS process is designed. The THD of the transconductor for a 0.7 V_pp input, is -50 dB at 10 MHz and about -62 dB at 1 MHz frequency. In the proposed transconductor structure, the whole circuit, apart from a DC level-shifter based on a voltage doubler, is biased by a single 1.5 V supply. Due to this structure, a high current voltage doubler is not required and the whole filter draws less than 70 μA current from this doubler making an on-chip voltage doubler feasible. Also, a new linear common-mode detector with high frequency response is designed to stabilize the output common-mode voltage. The entire filter chip exhibits an IM3 of -55 dB for 0.6 V_pp input signals and 1 MHz cut off frequency, with 20 mW power dissipation. The cut off frequency of the filter can be changed from below 1 MHz to about 10 MHz