A High-Loop-Gain Low-Dropout Regulator with Adaptive Positive Feedback Compensation Handling 1-A Load Current

Abstract

Low-dropout regulators, which have the capabilities of handling large output current and obtaining a superior transient response, are receiving increasing attention. This paper presents a high-output-current low-dropout regulator with high loop gain. An adaptive positive feedback compensation method is presented. It guarantees stability under full load conditions and achieves high loop gain. Without relying on an external zero, a ceramic capacitor with low equivalent series resistance can be employed, resulting in the minimized output voltage variation during the load transient response. In addition, the load regulation and line regulation are both small. An impedance adapting stage is inserted between the error amplifier and power transistor. It is suitable for low-supply voltage applications and drives the power transistor quickly. The simulation results indicate that the proposed LDO can supply a 1000 mA load current with a 200 mV dropout voltage. The load regulation and line regulations are 0.089 μV/mA and 0.562 m V/V, respectively. The power supply rejection is above 75 dB at 1 kHz under the full range of the output current.