| 摘要 |
PROBLEM TO BE SOLVED: To provide an amplifier circuit that is suitably used for a high gain AC amplifter circuit such as a non-contact card BPSK demodulation amplifier circuit, can reduce a time delay until an operation start of a differential amplification at start and eliminate time dependence of output waveform distortion. SOLUTION: At application of power, an intermediate level VOR between a level at an output terminal out1 and a level at an output terminal out2 is fed to peak hold circuits 113, 114, the peak hold circuit 113 charges an input coupling capacitor C1 and an AC bypass capacitor C2, the peak hold circuit 114 charges an AC bypass capacitor C3, and a control circuit 115 shuts off supply of a power supply voltage VCC to the peak hold circuits 113, 114 after a lapse of a prescribed period after the end of charging of the input coupling capacitor C1 and the AC bypass capacitors C2, C3.
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