Patent ID: 8390371

Claim:
A transconductance-capacitance (G m -C) filter, comprising: a plurality of operational transconductance amplifiers (OTAs), wherein each OTA includes a differential pair of transistors providing a tail current to a third transistor having a transconductance g m , and a bias circuit for biasing a gate of a given one of the third transistors with a control voltage, the bias circuit including a switched capacitor circuit such that a transfer function for the G m -C filter is proportional to a ratio of capacitances and is independent of process corner variations, wherein the bias circuit includes a fourth transistor matched to the given third transistor and a fifth transistor that has a width-to-length ratio that is a factor X times larger than a width-to-length ratio for the fourth transistor, and wherein the switched capacitor circuit is coupled between a source for the fifth transistor and ground.