| 摘要 |
PROBLEM TO BE SOLVED: To provide a physical quantity detecting circuit with a high resistance. SOLUTION: An operational amplifier 20 does a negative feedback action. Diodes 26, 28 and a condenser 24 are connected in parallel between an output terminal and reverse input terminal of the amplifier 20. The diodes 26, 28 are connected in series between the output and reverse input terminal so that they are mutually in opposite directions. A condenser 22 is variable in capacity. The diodes 26, 28 function as a high resistance.
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