TRANSMITTING POWER CONTROL CIRCUIT OF MOBILE COMMUNICATION UNIT

摘要

PURPOSE: A circuit for controlling a transmission output in a mobile communication device is provided to remove an error, and to decrease a level gain deviation by equipping a duplexer filter at an input stage and an output stage of an AGC(Automatic Gain Control) circuit. CONSTITUTION: A duplexer filter(5) receives input frequencies of a receive IF stage and an input frequency a transmit IF stage, and mixes a transmitting and receiving signal. At this time, the input frequencies of the receive IF stage and the input frequency of a transmit IF stage are different each other. An AGC(Automatic Gain Control) amp receives the mixed signal, and amplifies the mixed signal to a wanted value. After this, the AGC amp(6) transmits the mixed signal to another duplexer filter(5), and operates an AGC(7) by separating some part of the mixed signal. Another duplexer filter(5) separates the transmitting and receiving signal. Another duplexer filter(5) controls a transmission output by transmitting the separated transmitting signal to a transmit IF output and transmitting the separated receiving signal to a receive IF input.