| 摘要 |
PURPOSE:To eliminate the non-linearity of detection output characteristic caused by the DC off-set of an carrier amplifier by providing a condenser between the output of a second carrier amplifier which amplifies the output of the first carrier amplifier and a ground. CONSTITUTION:A resistor is provided between the single end output of the carrier amplifier 2 and the differential input of a multiplier 5 and the capacitor C is provided between one side input of the multiplier 5 and the ground Therefore, a direct current component among the output of the carrier amplifier is inputted with in-phase and only one side of an alternation current component is transmitted to the multiplier 6. As the result, when the DC off-set caused by the variance of semiconductor process occurs in the output of the carrier amplifier 1, that is suppressed, because of the single end output of the carrier amplifier 2. Thus, the non-linearity of the detection output characteristic is eliminated and the deterioration of the detection characteristic can be suppressed.
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