Low quiescent current capacitor-less LDO regulator with high slew rate super class AB CMOS OTA

Abstract

This paper presents a low quiescent current capacitor-less low-dropout regulator (LDO) with high slew rate super class AB CMOS operational transconductance amplifier (OTA). The OTA of this design is based on the combination of class AB differential input stages and local common-mode feedback (LCMFB) which provides additional dynamic current boosting, increased gain-bandwidth (GBW) product and slew rate (SR). LCMFB is applied to various class AB differential input stages, leading to different class AB OTA topologies. The design also uses dynamic charging transistor (DCT) to enhance the transient characteristics of the circuit. The presented LDO is fabricated in a 0.18 um standard CMOS process. The circuit consumes a quiescent current of 10 uA at no load, regulating the output at 1.0V with maximum output current of 100mA from a voltage supply of 1.2V. It achieves full range stability from 1mA to 100mA load current at a maximum 100pF load capacitor.