Patent ID: 7277518

Claim:
A phase-locked loop (PLL) comprising: a voltage controlled oscillator including a varactor having a first set of capacitor cells configured to adjust a capacitance based on a first control voltage, and a second set of capacitor cells configured to adjust a capacitance based on a second control voltage; and a charge-pump loop filter configured to receive a first and a second update signal each having at least one state based on a phase difference between a first clock and a second clock, and comprising: a first component configured to adjust, during an update period, a voltage across an impedance from a reference level based on the states of the first and second update signals and to return the voltage across the impedance to the reference level prior to an end of the update period, wherein the voltage across the impedance comprises the first control voltage; and a second component configured to adjust a voltage across a capacitor based on the states of the first and second input signals, wherein the voltage across the capacitor comprises the second control voltage.