| 摘要 |
PROBLEM TO BE SOLVED: To accomplish an amplifier circuit capable of adjusting amplitudes of output signals outputted from a first amplifier and a second amplifier so as to be always even to each other by changing the gain of the first amplifier or the second amplifier, thereby reducing the noise index of the amplifier circuit and improving a reception sensitivity. SOLUTION: In the amplifier circuit, the output signal of the second amplifier (phase inversion amplifier) 101 and the output signal of the first amplifier (in-phase amplifier) 102 are inputted to a detection circuit 103 and a detection circuit 104, information of amplitudes is detected and the information of the amplitudes is inputted to an AGC control circuit 105. On the basis of a difference between the amplitude of the output signal of the phase inverted amplifier 101 and the amplitude of the output signal of the in-phase amplifier 102, the AGC control circuit 105 then changes a gain of the phase inverted amplifier 101 and adjusts the amplitude of the output signal of the phase inverted amplifier 101 to be equal with the amplitude of the output signal of the in-phase amplifier 102. COPYRIGHT: (C)2008,JPO&INPIT
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