Patent ID: 7667553

Claim:
A frequency modulator, comprising: a voltage-controlled oscillator which oscillates at a frequency according to a voltage applied to an input terminal; a divider which divides an output signal of said voltage-controlled oscillator; a phase comparator which compares the output signal of said divider with a reference clock signal and outputs a voltage corresponding to a phase difference between the output signal thereof and the reference clock signal; and a loop filter, provided on a path leading from an output terminal of said phase comparator to the input terminal of said voltage-controlled oscillator, which removes a high-frequency component of an output voltage of said phase comparator, wherein a terminal for inputting a modulation signal is provided in said loop filter, separately from a terminal connected with the path leading from the output terminal of said phase comparator to the input terminal of said voltage-controlled oscillator; and wherein the modulation signal is a stereo composite signal.