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 0.6um standard CMOS process is designed. The THD of the transconductor for a 0.7V(pp) input, is -50dB at 10-MHz and about -62dB at 1-MHz frequency. In the proposed transconductor structure, the whole circuit, apart from a de 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 70uA 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 -55dB for 0.6Vpp 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.