A 0.8-V 1.2-μW rail-to-rail fully differential OpAmp with adaptive biasing

This paper presents an ultra low-power rail-to-rail fully differential operational amplifier (OpAmp) fabricated in a standard 0.18 μm CMOS technology. The proposed circuit uses transistors biased in the sub-threshold region for low-voltage low-power operation. For a 0.8 V single supply and 8 pF loads, experimental measurements shows a 51 dB open loop gain, 62° phase margin, 57 kHz unity gain frequency and a 750 mV linear output swing. Adaptive biasing provides 0.14 V/μs slew-rate, while a 73 dB CMRR is achieved thanks to a CMFF circuit, demonstrating the correct functionality of the OpAmp with a power consumption of 1.2 μW.