DIGITAL AMPLITUDE MODULATION AMPLIFIER

PROBLEM TO BE SOLVED: To obtain the amplitude modulation amplifier by which an amplitude- modulated signal is produced efficiently and the amplitude-modulated signal reproduced with fidelity to an amplitude of an input modulation signal is outputted. SOLUTION: Since an output voltage (e) of a coupler CU2 is shifted by a phase of -135 deg. with respect to input signals c, d (-270 deg. with respect to input signals a, b), a carrier being a signal (f) is shifted by -270 deg. with a phase shifter 1 to make the signal (f) in phase to the signal (e). Power of the signals f, e are combined by a 3dB coupler M1 and the phases are shifted and controlled by variable phase shifters PH11, PH12 so as to be in phase to each other, and an output signal of the variable phase shifter PH11 is shifted by -900 deg. at a phase shifter SH1, and then the resulting signals f, e are controlled to have a phase difference of -90 deg. and given to a 3dB coupler M2. Thus, the received two signals e, f are outputted as output voltages EOUT.