Patent ID: 7295078

Claim:
A tuning circuit comprising: a voltage controlled oscillator for generating a first clock signal comprising: an inductive element; a variable capacitive element coupled to the inductive element; a bank of switched capacitors coupled to the inductive element and the variable capacitive element; a frequency divider for generating a second clock signal responsive to the first clock signal and a selected divisor; frequency control circuitry for adjusting a control voltage to the variable capacitive element responsive to a frequency difference between the second clock signal and a reference signal to oscillate the first clock signal at a desired frequency; and logic circuitry for calibrating the voltage controlled oscillator to a frequency range inclusive of a new desired frequency responsive to a change in the divisor by: performing a coarse search by operating the voltage controlled oscillator at a single predetermined control voltage for various capacitive settings of the bank to determine an initial control word for configuring the bank; and testing the initial control word to determine whether the initial control word should be used to generate the first clock signal at the new desired frequency or whether the initial control word should be changed to an adjacent control word to generate the first clock signal at the new desired frequency.