A fast-transient response capacitor-less LDO regulator with undershoot/overshoot voltage detection and transient-current enhanced circuit

Abstract

The traditional capacitor-less LDO is analyzed and a fast-transient response capacitor-less LDO with transient-current enhanced circuit is proposed in this paper. The overshot/undershot voltage can be detected when the load current makes changed, the transient-current enhanced circuit, based on AC couple network, can achieve high charging/discharging current of the gate of power transistor to improve the transient of the LDO. Based on the proposed frequency strategy, the on-chip compensation capacitor required is reduced and the area of the chip is minimized. The circuit is simulated in a 0.13μm standard CMOS and the quiescent current is 30 μA. When the load current changes from 1-50mA at 1μs, the maximum overshot (undershot) voltage is 79mV (46mV) Compared to the LDO without transient enhance circuit, it is improved 60.5% and 58.2%, respectively.