A Single-Controller-Four-Output Analog-Assisted Digital LDO with Adaptive-Time-Multiplexing Control in 65-nm CMOS

This paper presents a single-controller-four-output analog-assisted digital LDO which can regulate four output voltage domains by sharing only one digital controller with an adaptive-time-multiplexing control scheme. The area of the digital controller is 62% smaller compared to the sum of the digital controller area of four independent LDOs. An analog-assisted loop and a push-pull auxiliary loop are used to take over the control in steady state to save quiescent power, reduce output ripple and enhance the response speed. A prototype is fabricated in a 65nm CMOS process. An undershoot voltage of 100mV is measured with a 47mA/20ns load step, resulting a figure-of-merit as low as 0.12ps.