Fast-Response Low-Voltage NMOS Low-Dropout Regulator Using Coarse and Fine Charge Pumps with Double Driving and High-Frequency Internal Oscillator

Abstract

A fast-response low-voltage NMOS low-dropout regulator (LDO) with coarse-fine charge-pumps and double driving-high frequency internal oscillator is proposed. It regulates the gate voltage of the power transistor through coarse and fine charge-pumps with three comparators for detecting coarse-fine modes. It achieves fast response time and low quiescent power loss. It has a low undershoot voltage with fast settling time employing a high-speed internal ring oscillator driving the coarse and fine charge-pumps. The LDO circuit is implemented with a 65 nm CMOS process. It generates 0.45 V output voltage from 0.5 V supply voltage. It has the simulation results of an overshoot of 34 mV, an undershoot of 69 mV, and a settling time of 28 ns under the load transient from 15 mA to 45 mA with a 1 ns edge.