0.7-V Three-Stage Class-AB CMOS Operational Transconductance Amplifier

A simple high-performance architecture for bulk-driven operational transconductance amplifiers (OTAs) is presented. The solution, suitable for operation under sub 1-V single supply, is made up of three gain stages and, as an additional feature, provides inherent class-AB behavior with accurate and robust standby current control. The OTA is fabricated in a 180-nm standard CMOS technology, occupies an area of $19.8\cdot 10^{-3}\ \text{mm}^{2}$ and is powered from 0.7 V with a standby current consumption of around 36 $\mu\text{A}$. DC gain and unity gain frequency are 57 dB and 3 MHz, respectively, under a capacitive load of 20 pF. Overall good large-signal and small-signal performances are achieved, making the solution extremely competitive in comparison to the state of the art.