Method and apparatus for cancelling interconnection capacitance
Abstract:
The present invention relates to a method for cancelling effects of changes in interconnection capacitances on capacitive sensor readings, and an apparatus configure to perform such method. The sensor readings are provided by a capacitive sensor connected with an interface circuitry. The interface circuitry has at least two interconnections comprising a sensor interconnection and a compensating interconnection. The method comprises obtaining a total sensor capacitance value from the capacitive sensor, and obtaining a total compensating interconnection capacitance value from the compensating interconnection, calculating a compensated sensor capacitance value by reducing the obtained total compensating interconnection capacitance value multiplied with a weight coefficient from the obtained total sensor capacitance value and providing at an output of the interface circuitry an electrical signal corresponding to the compensated sensor capacitance value. The weight coefficient is independent of changes of relative permittivity in the immediate environment of the capacitive sensor and its interconnections.
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