Patent ID: 7019540
Filing Date: 2006-03-28
Classification: G01R,H04R

Abstract:
1. An electrostatic capacitance detection circuit that outputs a detection signal corresponding to electrostatic capacitance of a capacitor to be detected, comprising: an impedance converter of which input impedance is high and output impedance is low; a first capacitive impedance element; an operational amplifier; an AC voltage generator that applies AC voltage to the operational amplifier; and a signal output terminal that is connected to an output of the operational amplifier, wherein an input terminal of the impedance converter is connected to one end of the capacitor and one end of the first capacitive impedance element, the first capacitive impedance element and the impedance converter are included in a negative feedback loop of the operational amplifier, and the capacitor and the electrostatic capacitance detection circuit are located adjacently.