250mV Supply-Voltage Digital Low-Dropout Regulator using Fast Current Tracking Scheme.

This paper proposes a 250mV supply-voltrage digital low-dropout (LDO) regulator. The proposed LDO regulator reduces the supply voltage to 250mV by implementing with all digital circuits in a 0.11µm CMOS process. The fast current tracking scheme achieves the fast settling time of the output voltage by eliminating the ringing problem. The over-voltage and under-voltage detection circuits decrease the overshoot and undershoot voltages by changing the switch array current rapidly. The switch bias circuit reduces the size of the current switch array to 1/3, which applies a forward body bias voltage at low supply voltage. The fabricated LDO regulator worked at 0.25~1.2V supply voltage. It achieved 250mV supply voltage and 220mV output voltage with 99.5% current efficiency and 8mV ripple voltage at 20~200µA load current. [ABSTRACT FROM AUTHOR]