Patent ID: 7215215

Claim:
A two point phase modulation apparatus comprising: a PLL circuit; a first adder that adds a baseband modulation signal and a carrier frequency signal; a frequency divider that is provided in the PLL circuit and sets a frequency division ratio of the PLL circuit based on an output of the first adder a second adder that is provided between a low pass filter and a voltage controlled oscillator in the PLL circuit and adds a voltage in accordance with the baseband modulation signal to an output voltage of the low pass filter and supplies a resulting voltage to a control voltage terminal of the voltage controlled oscillator; a phase detector that performs phase detection with respect to an RF phase modulation signal outputted from the voltage controlled oscillator; a comparator that compares a phase of the RF phase modulation signal after the phase detection with a phase of the baseband modulation signal and outputs a difference between the signals; and a gain controller that controls a gain of the baseband modulation signal based on an output of the comparator and outputs the gain-controlled baseband modulation signal to the second adder.