A Fast Transient and Low Power Capacitor-less Low-dropout Regulator using Advanced Dynamic Biasing Method

Abstract

A fast transient and low power capacitor-less low-dropout (LDO) regulator is proposed for power management in wearable applications. The proposed LDO regulator employs an advanced dynamic biasing (ADB) method, which detects the load transient without using external components including the large resistor and capacitor, and dynamically adjusts the bias current according to the load current (I-LOAD). In this way, it maintains the bias current low at steady state and increases it only during load transients, thus achieving a fast transient response while maintaining a low power consumption. The proposed LDO regulator was fabricated using a 0.18-mu m CMOS process and occupied a chip area of 0.05 mm(2). The measurement results showed that the proposed LDO regulator achieved an output voltage settling time of less than 1.2 mu s when I-LOAD changes from 100 mA to 100 mu A. In addition, the measured quiescent current was 2.0 mu A at light load. Therefore, the proposed LDO regulator is suitable for wearable applications requiring fast transient response and low power consumption.