Patent ID: 7336934

Claim:
A transmission modulation apparatus comprising: a high frequency power amplifier that amplifies a high frequency phase modulation signal of a high frequency signal; and a power source voltage controller that amplifies a baseband amplitude modulation signal of the high frequency signal and controls a power source voltage of the high frequency power amplifier, wherein the power source voltage controller comprises: a delta sigma amplifier that performs delta sigma amplifying of the baseband amplitude modulation signal and generates a delta sigma amplification signal; a delta amplifier that performs delta amplifying of the baseband amplitude modulation signal and generates a delta amplification signal; and a selector that selects the delta sigma amplification signal when the baseband amplitude modulation signal does not fluctuate and selects the delta amplification signal when the baseband amplitude modulation signal fluctuates in accordance with a modulation mode switching control signal that indicates whether or not the baseband amplitude modulation signal fluctuates.