| 摘要 |
The present invention intends to not only reduce a measurement error of a capacitive sensor but improve detection sensitivity, and includes: a detecting capacitor of which the capacitance is changed depending on pressure; a fixed capacitor having reference capacitance; an initial voltage application part that applies an initial voltage having a predetermined frequency to the detecting capacitor and the fixed capacitor; a first operational amplifier that outputs an output voltage based on a partial voltage applied to at least the detecting capacitor; a reference voltage generation part that generates a reference voltage that serves as a reference for a change in the output voltage of the first operational amplifier and has the same frequency as that of the initial voltage; a second operational amplifier that outputs an output voltage based on the difference between the output voltage of the first operational amplifier and the reference voltage; and a pressure operation part that operates a pressure from the amplitude of the output voltage of the second operational amplifier. |
