Patent ID: 7541879

Claim:
A system for compensating for a nonlinearity of a voltage-controlled oscillator, the system comprising: a loop filter operable to suppress a high-frequency component of an input modulated signal; a voltage-controlled oscillator operable to control an oscillatory frequency in accordance with a signal outputted from the loop filter so as to perform a frequency modulation on the input modulated signal; a feedback processing section operable to compare a frequency modulated signal outputted from the voltage-controlled oscillator with the input modulated signal and operable to control, based on a comparison result, the frequency of the input modulated signal to be inputted to the loop filter; and a nonlinearity-compensated section operable to retain a compensation table in which a voltage vtfc for setting a center frequency of the frequency modulated signal is associated with a voltage vtc of the signal outputted from the loop filter, and operable to add, when the frequency modulated signal is oscillated at a center frequency fc, a compensation value to the input modulated signal, the compensation value being calculated based on a difference between a pair of the voltage vtfc and the voltage vtc, in the compensation table, both of which are associated with the center frequency fc and another pair of the voltage vtfc and the voltage vtc, in the compensation table, both of which are associated with a frequency other than the center frequency fc.