| 摘要 |
PROBLEM TO BE SOLVED: To effectuate precise adjustment with good temperature characteristic and linearity and with high resolution by changing the voltage ratio of a voltage divider circuit, thereby increasing/decreasing charges stored in a capacitor and adjusting the input capacitance of an amplifier circuit. SOLUTION: An input capacitance C6 of an operational amplifier 1 is adjusted with utilization of a capacitor C7 and a voltage divider circuit 10. An input capacitance adjusting circuit is set which includes the voltage divider circuit 10, whose voltage dividing ratio set between an output terminal 52 and a ground potential point can be changed digitally and the capacitor set between a voltage dividing point of the voltage divider circuit and an input terminal of the operational amplifier 1. The input capacitance adjusting circuit adjusts the input capacitance C6 by changing the voltage dividing ratio of the voltage divider circuit 10. Accordingly, the input capacitance can be adjusted digitally. The circuit is adaptable to an automatically calibrating measuring apparatus by controlling the voltage divider circuit 10 with using a CPU.
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