Abstract: High performance on-chip voltage regulator designs are disclosed which have settling times which are fast enough to meet today's microprocessor/microcontroller requirements when they are entering an active mode from a passive mode. A first preferred embodiment provides a circuit in which a single pulse control signal is required to instantly raise Vy when the microprocessor is in the wake-up period. The circuit includes a charge pump, a differential amplifier, and a microprocessor connected to the power supply through a voltage regulating device. A second embodiment provides a circuit to stimulate Vint prior to CPU wake-up. The principle of operation of this embodiment is to stimulate the voltage regulating device prior to CPU wake-up. By stimulating (pulling down) the Vint node, the voltage regulating device will raise Vy and ready the microprocessor to draw a large current.