Patent ID: 7190231

Claim:
A high-performance charge-pump circuit for receiving phase detector outputs and generating an average current flowing into or flow out of the charge-pump circuit output node, comprising: a first current mirror circuit consisting of two diode-connected transistors on its input side, and two transistors for a first output current source and a current source transistor coupled to the charge-pump circuit output node for a second output current source, wherein the input side receives a reference current which is relatively independent of temperature, supply, and process variations and the two output sides provide the reference current; a second current mirror circuit consisting of a diode-connected transistor and a transistor on its input side, and a current source transistor coupled to the charge-pump circuit output node, wherein the input side of the second current mirror circuit is coupled to receive the reference current from the first output current source of the first current mirror circuit and the output side of the second current mirror circuit provides the reference current; a PMOS switch mirror circuit having a diode-connected reference transistor and a output transistor coupled to receive a switching signal and send the switching signal to the current source transistor of the second current mirror circuit; a NMOS switch mirror circuit having a diode-connected reference transistor and a output transistor coupled to receive a switching signal and send the switching signal to the second output current source transistor of the first current mirror circuit; and two switches for receiving the up and down signals from the phase detector, wherein each switch is coupled between a rail and a reference transistor of a switch mirror circuit.