Patent ID: 8618819
Filing Date: 2013-12-31
Classification: G01R

Abstract:
1. A capacitance detector comprising: a first capacitor which is an object to be detected and has fixed base capacitance and variable capacitance; a second capacitor charged with base charge corresponding to the base capacitance; third and fourth capacitors which receive capacitance distribution from the first or second capacitor; a first switching means for charging the first and second capacitors to a first fixed voltage and charging the third and fourth capacitors to a second fixed voltage in a first section and for charging the first and second capacitors to the second fixed voltage and charging the third and fourth capacitors to the first fixed voltage in a second section; a second switching means for separating the first and second capacitors from the third and fourth capacitors during a charge period in the first and second sections and for connecting the first and second capacitors to the third and fourth capacitors in a one-to-one manner at a capacitance distribution timing in the first and second sections; and a differential amplifier to which first and second voltages corresponding to equalized charge, which is equalized by capacitors connected to each other by the second switching means and which is held in the third and fourth capacitors, are differentially input.