Low-Power Fast-Transient Capacitor-Less LDO Regulator With High Slew-Rate Class-AB Amplifier

Abstract

This brief presents a low-power fast-transient capacitor-less low-dropout regulator (CL-LDO) for system-on-a-chip applications. A low-quiescent-current class-AB amplifier with embedded slew-rate enhancement (SRE) circuit is proposed to improve both current efficiency and load transient performance. As the SRE circuit is directly controlled by the amplifier, only a minimum hardware overhead is required. The proposed CL-LDO is fabricated in a 0.18- ${\mu }\text{m}$ standard CMOS process. It occupies an active area of 0.031 mm2 and consumes a quiescent current of $10.2~\mu \text{A}$ . It is capable of delivering a maximum load current of 100 mA at 1.0-V output from a 1.2-V power supply. The measured results show that a settling time of $0.22~\mu \text{s}$ is achieved for load steps from 1 mA to 100 mA (and vice versa) with an edge time of $0.1~\mu \text{s}$ .