A compact CMOS Gm-C biquadratic cell for chopper amplifier band limiting

We present a compact Gm-C biquadratic cell with fully differential input/single-ended output for continuous time low pass filtering and channel bandwidth selection in integrated sensor interfaces. Transconductors with input MOSFETs operating in triode region allow the filter to operate at very low cut-off frequencies without excessive area occupation. The noise versus input range issue is originally addressed in order to provide useful design formulas. Electrical simulations successfully demonstrate the application of the filter as a cascade stage after a chopper modulated amplifier.