Patent ID: 8154350

Claim:
An apparatus comprising: a voltage controlled oscillator (VCO) having: a capacitive network that receives a first tuning voltage that is based at least in part on an input signal; and a switched capacitor array that is coupled to the capacitive network; an amplifier that receives the first tuning voltage and a reference voltage, wherein the amplifier amplifies the difference between the reference voltage and the first tuning voltage; a switch that receives the reference voltage and the amplified difference between the reference voltage and the first tuning voltage; a calibration capacitor that receives the output from the switch and generates a second tuning voltage; and a control loop that receives the input signal and the second tuning voltage, wherein the control loop controls the switch so as to apply the reference voltage to the calibration capacitor when the apparatus resets, and wherein the control loop controls the switched capacitor array so as to adjust the capacitance of the VCO to generally maintain phase and frequency lock.