Communication apparatus utilizing high power amplifier

A communication apparatus comprising:

• a semiconductor power amplifier integrated circuit with a junction type field effect transistor having an input terminal and a gate bias terminal to which a gate bias voltage is applied for controlling current flowing through said power amplifier circuit;
• a main controller providing both a high-frequency variable input signal having a variable magnitude to said input terminal of said power amplifier circuit and a control signal voltage;
• a detector for extracting a part of said high-frequency variable input signal supplied from said main controller and performing a direct current (DC) detection of the extracted high-frequency signal to thereby output a variable DC voltage related to the magnitude of said variable high-frequency signal;
• a gate bias generator for receiving the variable DC voltage output from said detector and converting the variable DC voltage thereby to generate a variable gate bias voltage which varies in magnitude in accordance with the variable DC voltage;
• and an adder having a first input terminal to which said control signal voltage is applied from said main controller and a second input terminal to which said variable gate bias voltage is applied for obtaining a sum of the input control signal voltage and the input gate bias variable voltage, thereby to apply the sum to said gate bias terminal of said semiconductor power amplifier integrated circuit, whereby when power of the high-frequency signal is small, the gate bias voltage applied to the power amplifier circuit is low, and vice versa.