Patent ID: 7747230

Claim:
A transmission modulation apparatus comprising: an amplitude/phase data generating section that generates a baseband amplitude signal and a baseband phase signal; a phase modulator that phase-modulates a high-frequency signal using the baseband phase signal; a high-frequency power amplifier that amplifies an output signal of the phase modulator based on an output signal from a power supply voltage control section; the power supply voltage control section that calculates a power supply voltage value for controlling a power supply voltage of the high-frequency power amplifier based on the baseband amplitude signal, adds a predetermined offset voltage to the power supply voltage value, and outputs the result to the high-frequency amplifier as the output signal; a determining section that determines from execution conditions whether or not offset voltage correction for correcting the offset voltage is performed; and an offset voltage correcting section that, when the offset voltage correction is determined to be performed by the determining section, corrects the offset voltage using a first line, obtained by collinear approximation in a region where a relationship between the power supply voltage and an output voltage of the high-frequency power amplifier is non-linear, having a different slope from a slope of a second line in a region where the relationship is linear.