A Wide-Load-Range High-PSR Capless Low-Dropout Regulator with Adaptive Supply-Ripple Cancellation

For higher power density, the switching frequency of pre-stage DC-DC converters has evolved to be greater than 1MHz, requesting low dropout (LDO) regulators must have high power supply rejection (PSR) over a wider frequency range. In this paper, we propose a capless LDO regulator with an adaptive negative capacitance generation circuit to achieve high PSR over wide load and frequency ranges. The proposed LDO regulator is designed using a $0.18 \mu \mathrm{~m}$ CMOS process. Simulations results show that the proposed LDO regulator achieves greater than -60dB PSR at 100kHz and greater than -40dB PSR at 1 MHz over a load range of $500 \mu \mathrm{~A}$ to 50mA, with a total on-chip capacitance of only 105pF.