HIGH-FREQUENCY POWER AMPLIFIER, TRANSMITTER USING IT AND MOBILE-BODY COMMUNICATION TERMINAL

摘要

PROBLEM TO BE SOLVED: To provide a small-size high-frequency power amplifier holding an excellent linearity regardless of the fluctuation of a load impedance. SOLUTION: An AC voltage amplitude at an output terminal for a final-amplifying step transistor is detected, and a signal inhibiting the input-signal amplitude of the power amplifier is output when the voltage amplitude exceeds a predetermined threshold value. A reflection is generated towards the power amplifier from an antenna while depending upon the peripheral status of the antenna. The reflection appears as the fluctuation of the load impedance of the power amplifier. A mismatch generated by the fluctuation of the load impedance can be prevented. COPYRIGHT: (C)2007,JPO&INPIT