A Capacitor-less LDO With Fast-transient Error Amplifier and Push-pull Differentiator

摘要

This paper presents a fully-integrated and fast-transient capacitor-less low-dropout regulator (LDO) with high loop gain and bandwidth in full load range for SoC application. It utilizes a combination of a signal- and transient-current boosting (STCB) error amplifier (EA) with transient enhancement circuit (TEC) and a push-pull differentiator to drive gate capacitance of the power transistor. The STCB-based EA with TEC ensures fast response of the regulator and the differentiator is also adopted to enhance the loop stability while improving transient response simultaneously. Moreover, adaptive biasing is implemented in the circuit to compensate decrease of loop gain and bandwidth at heavy load. The proposed LDO is fabricated in a 0.5μm CMOS process and occupies an active chip area of 0.077mm~2. Simulation results demonstrate that it can deliver 100mA load current at 100mV dropout voltage. The voltage spike at the output, undergoing a maximum load current change, is controlled below 300mV and good line/load regulation is achieved at the same time.