| 摘要 |
PROBLEM TO BE SOLVED: To provide an oscillation type sensor detection circuit having no trouble factors for converting it into an ASIC by minimizing current/voltage converting operation and mainly using computing operation with a current signal for simplifying the circuit. SOLUTION: The oscillation type sensor detection circuit amplifies an AC electromotive force signal from an oscillation type sensor having a natural oscillation frequency which is changed depending upon a physical quantity to be measured and applies the amplified output as an excitation signal for the oscillation type sensor to cause self-oscillation. It comprises a voltage/current conversion circuit for converting the AC electromotive force signal into an AC current signal, a current/voltage conversion circuit for converting a first current signal proportional to the AC current signal into a voltage signal, a gain control conversion circuit for inputting the voltage signal and supplying the excitation signal to the oscillation type sensor, an absolute value circuit for generating a second current signal proportional to the absolute value of the AC current signal, and an integration circuit for inputting the second current signal to generate a third current signal for controlling the gain of the gain control conversion circuit. COPYRIGHT: (C)2004,JPO
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