A Power Management System Based on Adaptive Low-Dropout Voltage Regulator with Optimal Reference Pre-Compensation Technique

This paper presents an adaptive dropout voltage regulator based on a constant on-time buck converter that improves the light load efficiency. By regulating the gate voltage of the pass transistor of the low dropout regulator (LDO), the dropout voltage is automatically minimized depending on the load current, increasing the end-to-end power conversion efficiency at the light load condition by 11.3%. The proposed direct-charging scheme and simple undershoot detector reduce the droop and improve the efficiency of the LDO. The reference pre-compensation technique is proposed to improve the ripple performance by compensating the reference voltage based on the on-time pulses. The proposed voltage regulator was fabricated by a 0.18-wm CMOS process and occupies 0.2874 mm2.