Frequency synthesizer, wireless communications device, and control method

摘要

A plurality of control voltages V 1 to V 3 are sequentially applied to a VCO 5 so as to obtain, for each of these control voltages, the operating reference voltages Vref 1 to Vref 3 for the variable capacitor elements VC 51 to VC 56 with which the difference between the oscillation frequency of the VCO 5 and the target frequency is minimum. With this operation, the frequency synthesizer of the present invention can not only set the oscillation frequency of the VCO 5 for a single control voltage to a desirable value but also set the control sensitivity at the oscillation frequency of the VCO 5 with varied control voltage to a desirable value.