CAPACITIVE PHYSICAL QUANTITY DETECTOR

A capacitive physical quantity detector includes: a capacitor having an electrostatic capacitance changeable with physical quantity; a converter converting a capacitance change to a voltage; and a selector having a comparator and a switching element. The converter includes a C-V converting circuit h...

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Hauptverfasser: MIKAMO KAZUKI, ITOU HIROKAZU
Format: Patent
Sprache:eng
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Beschreibung
Zusammenfassung:A capacitive physical quantity detector includes: a capacitor having an electrostatic capacitance changeable with physical quantity; a converter converting a capacitance change to a voltage; and a selector having a comparator and a switching element. The converter includes a C-V converting circuit having an operational amplifier for amplifying a first signal from the capacitor, a main switch between input and output terminals of the operational amplifier, feedback capacitors and feedback switches. Each feedback switch connects a feedback capacitor to the main switch when the feedback switch is closed. The selector closes the feedback switches based on a second signal of the converter. The comparator compares the second signal with a threshold voltage. The switching element switches the feedback switches according to a third signal from the comparator to set the second signal smaller than a saturated voltage and larger than the threshold voltage.