| 摘要 |
A capacitance detection circuit (7) is provided with: a CV conversion circuit (8) that is configured from a whole differential amplifier (11) and feedback capacitors (Cf1, Cf2); an input common mode feedback circuit (9), which has a reference voltage input terminal (14), and which controls an average voltage of an inverting input terminal and a non inverting input terminal of the whole differential amplifier (11) to a voltage to be inputted to the reference voltage input terminal (14); and a reference voltage generating circuit (10) that outputs a reference voltage signal to the reference voltage input terminal (14), said reference voltage signal changing at a higher frequency than a resonant frequency of an oscillator (4). |
