Patent ID: 7161401

Claim:
A charge pump circuit comprising: a charge pump having a charge pump output; wherein the charge pump includes a first switch driven by a differential UP signal coupled to a second switch driven by a differential DOWN signal; wherein the charge pump includes a first tail current source coupled between a supply voltage and the first switch, and wherein a second tail current source is coupled between a ground and the second switch; wherein the charge pump includes an operational amplifier having an amplifier output and an amplifier input, wherein the amplifier output is coupled to one of the first tail current source and the second tail current source; a low pass filter coupled to the charge pump output, wherein the low pass filter includes a resistor-capacitor network and wherein an output between a resistor and a capacitor of the resistor-capacitor network is coupled to the amplifier input; and a replica circuit that adjusts the first tail current source and the second tail current source in the charge pump, wherein the output between the resistor and the capacitor of the resistor-capacitor network provides feedback to the replica circuit.