| 摘要 |
PROBLEM TO BE SOLVED: To enable long-time wait by suppressing a bias current at an amplifier or frequency converter into required sufficient operating current by varying a reception band when the occurrence of third-order mutual modulation distortion can be considered. SOLUTION: When the strong signals of an analog system are simultaneously inputted during communication in a code division multiple access(CDMA) system, the third-order mutual modulation distortion occurs because of non-linear distortion in a reception circuit. A control circuit 5 compares CDMA pilot strength provided by a base band signal processing circuit 6 with the strength of a received signal from a variable gain amplifier circuit 15 and when the occurrence of third-order mutual modulation distortion is detected, a filter 4 for analog system band is parallelly connected by controlling a changeover switch 3 between a duplexer 2 and a low noise amplifier 11 so that the signal of an analog system channel is attenuated. Since the third-order mutual modulation distortion can be reduced, it is not necessary to expand the dynamic range of a reception system and a low bias current is sufficient. |
