Phase modulator with gain control

摘要

In a method for generating a transmitting wave, a power supply voltage (Vcc) to be supplied to a transmission power amplifier (3) is detected by a voltage detector (11), and a modulating signal (Sm) is controlled so that a peak value of a modulated wave (St) is lowered in accordance with a reduction amount of the power supply voltage (Vcc). Since the peak value of the modulated wave input to the power amplifier (3) is lowered, it is possible to obtain a transmitting wave without a distortion of the wave form or an increased bandwidth even when the reduction in the power supply voltage involves the lowering of the driving capability of the power amplifier. <IMAGE>