High current efficiency class-AB OTA with high open loop gain and enhanced bandwidth

An efficient class-AB OTA with enhanced output current, slew rate, open loop gain, and gain bandwidth is presented. The circuit is based on a class-AB input stage with adaptive biasing, and an output stage with dynamically biased cascode transistors. It can deliver output currents 100 times larger than the bias current with a total quiescent power dissipation of 72 µW. Measurement results of a 180 nm CMOS test chip prototype show slew rate, gain bandwidth, and open loop gain enhancement.