Approaching to the antenna amplifier, the shared antenna amplifier and

摘要

PROBLEM TO BE SOLVED: To receive weak signals with a high sensitivity and reduce distortion or signal suppression when there is a strong interfering signal.;SOLUTION: When amplifying a high-frequency signal received by an antenna 10 by means of an antenna amplifier 11, an output switching circuit 15 switches a switching circuit 16 from the output side of an amplifier 12 to a through circuit 14 if there is a strong electric field, a strong interfering wave, and the like. The through circuit 14 leads the high-frequency signal inputted into the amplifier 12 directly to the output side without getting it through the amplifier. Even though attempting to amplify a high-frequency signal to be received by means of the amplifier 12, input distortion is caused by inter-modulation or cross-modulation if there is a strong electric field, a strong interfering wave, and the like. By switching the switching circuit 16 to the through circuit, such input distortion can be improved. If the switching of the switching circuit 16 is done based on low frequency components highly correlated with distortion components generated by inter-modulation, more appropriate switching can be realized.;COPYRIGHT: (C)2003,JPO