| 摘要 |
PROBLEM TO BE SOLVED: To provide a method whereby a selection range of constituent parts can be expanded by preventing a physical quantity-converting circuit having a pressure sensor or the like from being dependent on a circuit power source to calculate measured signals. SOLUTION: This circuit comprises the pressure sensor means, a differential amplifier, an integrator and a comparator with a hysteresis width of Vhys. The circuit includes a switching means for switching connection of the pressure sensor means and a predetermined constant voltage Va between a measurement time and a zero adjustment time. The comparator calculates an output signal (pressure signal) Sout from a ratio of an output signal fout-s when the switching means is switched to the side of the measurement time and an output signal fout-z when the switching means is switched to the side of the zero adjustment time.
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