Patent ID: 8554160

Claim:
An AM (Amplitude-Modulated) transmitter comprising: an amplifying unit configured to receive a gain controlling signal, to modulate a carrier wave by using the gain controlling signal, to amplify the modulated signal according to the gain controlling signal, and to output a transmitting signal; a detecting signal generating unit configured to detect the transmitting signal output by the amplifying unit and to generate a detecting signal upon detecting the transmitting signal; and a gain controlling unit configured to receive a modulating signal having a level independent from a level of a receiving signal, to compare a level of the detecting signal with a level of an added signal generated by an addition of a reference signal and the modulating signal, based on the comparison, to generate the gain controlling signal, and to transmit the generated gain controlling signal to the amplifying unit, wherein the gain controlling unit is further configured to determine a difference between a level of the detecting signal and a level of the added signal, and based on the level difference, to generate a gain controlling signal that makes the level difference approach zero, and an operation of variable gain amplification of the amplifying unit to serve as an amplitude-modulation of the carrier wave and power amplification.