Low drop-out voltage regulator with full on-chip capacitance for slot-based operation

This paper presents a full on-chip low-dropout voltage regulator (LDO) for slot based applications like e.g. digital cordless telephones. The LDO uses a floating and charged capacitor to drive the gate of an nMOS pass transistor. The LDO has been integrated in a 0.18 mum CMOS technology. The LDO is designed for 20 mA output current with a 200 mV dropout voltage and occupies 0.033 mm² of die area. The output voltage varies only a few milli Volt when a 5 mA load step or 500 mV input step is applied to the circuit. The LDO is stable for output currents in the complete range from 0 mA to 20 mA and does not require an external load capacitor. The LDO can operate for tens of milli seconds without recharging the floating capacitor.