Abstract: A digital AM transmitter according to the invention converts a audio signal to a digital audio signal of a plurality of bits by an A/D converter, outputs a logical code signal of "1" from each of those output terminals of a code unit, whose number corresponds to the digital value of the digital audio signal, selectively generates driving signals from those output terminals of a code shifter which are equal in number to the logical code signals of "1" from the code unit, while changing the driving-signal-generating output terminals of the code shifter from one to another (or some to others) with the lapse of time, selectively guiding, with the use of carrier wave switches, those portions of a carrier wave signal which have been divided by a carrier wave divider, to power amplifiers in accordance with driving signals generated from the code shifter, amplifies the guided portions of the carrier wave signal by power amplifiers, combined the amplified portions of the carrier wave signal by a combiner, and passes t

Abstract: A matching circuit is connected between a source circuit and a load circuit. The matching circuit is made up of an impedance transforming circuit and a balance-to-unbalance signal-transforming circuit. If necessary, means for blocking the DC components intervene between those transforming circuits. The impedance transforming circuit is made up of inductive and capacitive elements. The matching circuit is reversible.