Digital amplitude modulation amplifier and television broadcasting machine

摘要

Since output voltage e of coupler CU2 is displaced in phase by -135 degrees from input signals c and d (by -270 degrees from signals a and b), a carrier which makes signal f is phase shifted by -270 degrees by phase shifter phi 1 so that signal f may have the same phase as signal e. Signal f and signal e are power composed by first 3 dB coupler M1, and are further phase shift controlled by variable phase shifters PH11 and PH12 so that they may have the same phase. Further, an output signal of variable phase shifter PH11 is phase shifted by -90 degrees by phase shifter SH1 so that it has a phase difference by 90 degrees from an output signal of variable phase shifter PH2, and the two signals controlled in this manner are inputted to 3 dB coupler M2. Consequently, two signals e and f inputted to the amplifier are all outputted as output voltage EOUT. According to the present invention of a television broadcasting machine, since a carrier is phase modulated and amplitude modulated with amplitude information and phase information obtained from an input video signal, a vestigial side band signal is outputted to form a television signal without using vestigial side band.