Patent ID: 8040175

Claim:
An apparatus, comprising: a charge pump circuit; a clock driver coupled with the charge pump circuit, wherein the clock driver is configured to provide a regulated clock signal having a constant frequency to the charge pump circuit; and a voltage regulator coupled with the charge pump circuit, the voltage regulator comprising: an amplifier configured to provide an output voltage of the amplifier corresponding to a difference between a reference voltage and a voltage that is proportional to the output voltage of the charge pump circuit; and a transistor, wherein a gate of the transistor is coupled with the output voltage of the amplifier, a source of the transistor is coupled with a voltage source, and a drain of the transistor is configured to provide the regulated supply voltage, the voltage regulator configured to maintain an output voltage of the charge pump circuit near a target voltage by applying a regulated supply voltage to a voltage input of the charge pump circuit and to a voltage input of the clock driver, wherein the voltage regulator adjusts the regulated supply voltage in response to the output voltage of the charge pump circuit, the regulated supply voltage to increase when the output voltage of the charge pump circuit decreases and the regulated supply voltage to decrease when the output voltage of the charge pump circuit increases, wherein the constant frequency of the regulated clock signal is independent from the output voltage of the charge pump circuit.