Fast transient response CFA-based LDO regulator

Abstract

In this paper a fast transient response low-dropout regulator (LDO) based on a current feedback amplifier (CFA) is presented. The utilized CFA consists of an open-loop voltage follower with output local current-current feedback based on a level-shifted flipped voltage follower (LSFVF) to achieve high regulation and fast transient response. The inverting output buffer stage of the CFA together with current-mirror-based driving of the power pass transistor results in high PSRR. The circuit does not require any internal compensation capacitor and is stable for a wide range of output load currents 0-100 mA and a 1μF output capacitor. Post-layout simulation results for a 0.35μm CMOS process reveal that the maximum output voltage deviation of the proposed LDO for 0-100mA load transient with rise and fall times of 10 and 100ns is only 3mV, and the PSRR is smaller than -56dB over the entire load current range.