TRANSMITTER AND RADIO TELEPHONE SYSTEM

摘要

PROBLEM TO BE SOLVED: To prevent the fault of a circuit system to amplify power of a high frequency signal in advance. SOLUTION: In the case that a pre-stage of an amplifier 4, e.g. a band pass filter 1 or a driver 2 is faulty and the input to the amplifier 4 is extremely small, since a voltage VID is smaller than a voltage VP1 , application of an operation use voltage VCC to a power supply terminal of a comparator 6 is inhibited. Thus, the operation of the comparator 6 is stopped and application of the control voltage VC from the comparator 6 to the amplifier 4 is inhibited. Thus, the operation of the amplifier 4 is stopped and no excess current flows to the amplifier 4 and then faults/deterioration in the amplifier 4 are prevented in advance.