Transmission output amplifier

摘要

It is an object of the invention to control a bias current of each of the amplifying elements of an exciting section and a power amplifying section in accordance with a magnitude of an amplitude control signal. A value of a control signal which is supplied to a control signal input terminal is adjusted in accordance with a magnitude of a signal to be generated which is given by an amplitude control signal. Bias currents of transistors are adjusted by the control signal. Thus, an output voltage of the exciting section is variably controlled by a control signal. Further, gate voltages of transistors are adjusted by a voltage which is applied to a gate voltage terminal. Electric power, which can be output from the power amplifying section, is variably controlled.