| 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 multiplier. CONSTITUTION:The condenser C is provided between the output of the carrier amplifier 2 and the input of the multiplier 5. Therefore, only the alternating current component among the output of the carrier amplifier 2 is transmitted to the multiplier 5. 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 cut off by the capacitor C. 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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