Patent ID: 8183950

Claim:
A method of operating a phase-locked loop (“PLL”) including a voltage controlled oscillator (“VCO”), comprising: a) switching the VCO to an operating band selected from among the plurality of operating bands of the VCO; b) measuring a true center frequency at which the VCO oscillates in the selected operating band according to minimum and maximum frequencies corresponding respectively to minimum and maximum control voltages [CVmin, CVmax] by counting pulses in feedback from the output frequency of the VCO; c) allowing the PLL to lock the output frequency at a lock frequency when the lock frequency is within the selected operating band, and measuring the lock frequency by counting pulses in feedback from the lock frequency and determining a current difference between the measured true center frequency and the measured lock frequency; and d) so long as the current difference between the measured lock frequency and the measured true center frequency does not increase, switching the VCO to another operating band selected from among the plurality of operating bands of the VCO and repeating steps (b) and (c), otherwise setting the VCO to the operating band for which the difference between the measured lock frequency and the measured true center frequency is smallest, so as to select the operating band for which the measured lock frequency is closest to the true center of the frequency range of any of the operating bands, even if the output frequency of the VCO is a nonlinear function of the control voltage.