Abstract: A transmitter includes a phase control circuit configured to receive a first and a second modulation signals, and a power amplifier configured to receive a third modulation signal. The phase control circuit includes a variable frequency divider, a frequency division ratio being controlled by the first modulation signal; a frequency modulation D/A converter configured to modulate the frequency by the second modulation signal; and a voltage controlled oscillator, including a varactor, configured to receive a first control voltage based on the first modulation signal and a second control voltage based on the second modulation signal. At least one of a capacitance value of the varactor of the voltage controlled oscillator, a control bit number of the frequency modulation D/A converter, and a bias current value of the frequency modulation D/A converter is changed based on a data transfer rate.