Patent ID: 8907651

Claim:
A power supply circuit for providing a supply current to an electronic circuit, wherein the electronic circuit operates in a run mode and a standby mode and receives the supply current in the run mode, the power supply circuit comprising; a power regulator, connected to a core power supply and the electronic circuit, for regulating the supply current provided to the electronic circuit when the electronic circuit is in the run mode; a capacitor having a first terminal connected to the power regulator and a second terminal connected to ground, wherein the capacitor is charged to a predetermined voltage level by the core power supply when the electronic circuit transitions from the standby mode to the run mode; a refresh circuit, comprising: a first band gap voltage source for generating a voltage equivalent to the predetermined voltage level; and a first buffer amplifier having an input terminal connected to the first band gap voltage source and an output terminal connected to an inverted input terminal of the first buffer amplifier and to the first terminal of the capacitor; a first switch, connected between the refresh circuit and the first terminal of the capacitor, for connecting the refresh circuit to the capacitor when the electronic circuit is in the standby mode; and a second switch, connected to the refresh circuit and the first switch, for receiving a power regulator control signal and an oscillator signal, and controlling the first switch; wherein the refresh circuit maintains a voltage across the capacitor at about the predetermined voltage level when the electronic circuit is in the standby mode, thereby reducing time for the electronic circuit to transition from the standby mode to the run mode.