A 551-ns SETTLING TIME OUTPUT CAPACITOR-LESS LDO WITH PROTECTION CIRCUITS

Abstract

This paper proposes an output-capacitorless low-dropout regulator (OCL-LDO) with simple structure and fast load transient response for system-on-chip applications. The proposed OCL-LDO does not require output capacitance and remains stable at no-load condition. A combining frequency compensation technique is utilized to reduce on-chip compensation capacitor without degrading loop stability at light load and improve load transient response speed simultaneously. In addition, over-temperature, over-voltage, and short-circuit protection functions are also integrated into the OCL-LDO to ensure circuit safety during operation. The proposed OCL-LDO regulator has been implemented and simulated in a 180 nm CMOS process. Simulation results demonstrate the OCL-LDO regulates the output at 0.9 V from a voltage supply of 1.8 V. The protection circuits turn off the OCL-LDO when a problem occurs. The OCL-LDO consumes 71.6 μA quiescent current at light load and can recover within 655 ns for load transient from 0 to 100 mA and within 551 ns for load transient from 100 mA to 0 in 100 ns. The OCL-LDO obtains good load regulation of 2.54 µV/mA.