Patent ID: 6683462
Filing Date: 2004-01-27
Classification: G01R

Abstract:
An apparatus for measuring a capacitance, comprising:a voltage source having a current limiting function and capable of applying different voltages to the capacitance, the voltage source comprising a variable-output voltage source, a variable-output current source, and a current detector that is selectively connectable to said variable-output voltage source or said variable-output current source depending on a current flowing therethrough; and an integrator capable of continuous integration operation for repeatedly integrating a current flowing through the capacitance at constant periodic intervals the integrator comprising two constant current sources whose polarities are opposite to each other and are each connected through a switch to an input of an operational amplifier shunted by a capacitor having a known capacitance, and a comparator/counter connected to an output of the amplifier for turning the switch on and off.