| 摘要 |
PROBLEM TO BE SOLVED: To improve the temp. detection accuracy and allows the system constitution to be simplified. SOLUTION: The apparatus 1 comprises a ferroelectric capacitor 11, an integrator circuit 12 and comparator circuit 13 for detecting the temp. Square wave voltages Va, Vb over a withstanding electric field are applied between electrodes 11A, 11B of the ferroelectric capacitor 11 at specified intervals. The integrator circuit 12 converts the integrated value of the current or charge due to charging/discharging of the ferroelectric capacitor 11 to a voltage V1. The comparator circuit 13 outputs a PWM waveform and inverts the output of the PWM waveform at the time when the voltage V1 converted by the integrator circuit 12 is equal to a reference voltage V2. A digital processor circuit 14 measures this inversion time and a central processing circuit 3 can obtain the temp. from the measurement result.
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