Patent ID: 8310248

Claim:
A capacitive sensor device comprising: a first sensor capacitor and a second sensor capacitor coupled in series at a connection portion; a clock signal generating part that generates a first clock signal and a second clock signal, the first clock signal applied to an open end of the first sensor capacitor, the second clock signal applied to an open end of the second sensor capacitor; an operational amplifier having an inverting input terminal, a non-inverting input terminal, and an output terminal, the inverting input terminal coupled with the connection portion of the first sensor capacitor and the second sensor capacitor, the non-inverting input terminal applied with a reference voltage; a feedback capacitor coupling the output terminal and the inverting input terminal of the operational amplifier; a compensating capacitor coupled with the connection portion of the first sensor capacitor and the second sensor capacitor; and a compensating signal generating part that generates a compensating signal applied to an open end of the compensating capacitor, wherein: the first sensor capacitor and the second sensor capacitor have electrostatic capacitances that change in accordance with an applied physical quantity; the first clock signal and the second clock signal have a same frequency and a same amplitude and have phases being opposite each other; and the compensating signal has a frequency same as the first clock signal and the second clock signal, has a phase same as the first clock signal or the second clock signal, and has an amplitude that is adjustable.