| 摘要 |
PROBLEM TO BE SOLVED: To prevent a receiver that prevents a booster from being excessively inputted even though the wave number of an input high frequency signal to the booster is decreased. SOLUTION: A high frequency signal with the possibility that a wave number changes is supplied to an input terminal 2. The high frequency signal is attenuated by a variable attenuator 6, amplified by amplification stages 8a to 8c and supplied to an output terminal 14. A detection circuit 18 detects an output signal of the amplification stage 8c. The detected voltage becomes larger as the wave number of the high frequency signal supplied to the input terminal 2 becomes large. The detected voltage and a reference voltage are inputted to a comparison circuit 20. The comparison circuit 20 generates an output voltage that makes the attenuation amount of the variable attenuator 6 large when the detected voltage is larger than the reference voltage and makes the attenuation amount of the variable attenuator 6 small when the detected voltage is smaller than the reference voltage. An attenuation adjustment circuit 26 adjusts the output voltage so as to make the attenuation amount of the variable attenuator 6 larger than the attenuation amount of the variable attenuator 6 when a high frequency signal of a predetermined wave number is inputted to the input terminal 2. COPYRIGHT: (C)2006,JPO&NCIPI
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