A three-stage NMC operational amplifier with enhanced slew rate for switched-capacitor circuits.

This paper presents a new architecture for three-stage operational transconductance amplifiers (OTAs) with a class AB input stage to improve the slew rate. The nested Miller compensation scheme is utilized to stabilize the proposed OTA. A nonlinear current mirror in the first-stage is used to implement the class AB operation. Details of the proposed OTA are described and the circuit level simulation results are provided using HSPICE and a 90 nm CMOS technology to verify the usefulness of the proposed OTA. In comparison with the conventional class A OTA, it achieves 284.1% enhancement in the slew rate and the settling time is reduced from 15.7 ns to 9.1 ns with approximately the same power dissipation. [ABSTRACT FROM AUTHOR]