A 0.6 V class-AB rail-to-rail CMOS OTA exploiting threshold lowering

A class-AB OTA (operational transconductance amplifier) topology with rail-to-rail input common-mode range is proposed for application in very low-voltage applications. High efficiency is achieved by reusing transistors both for class-AB operation and for mirroring the output currents, and a threshold lowering technique is applied to allow supply voltages less than two threshold voltages. Simulations in 40 nm CMOS technology show 41 dB gain at ±0.3 V supply voltage, a unity-gain frequency of 8.8 MHz on a 5 pF load, class-AB behaviour and full rail-to-rail operation when closed in unity-gain buffer configuration.