A method for determining a sense impedance of a guard-sense capacitive sensor operated in loading mode, the sensor having an electrically conductive sense electrode and an electrically conductive guard electrode. The method includes: providing a periodic guard voltage to the guard electrode; sequentially providing periodic reference voltages Vrefi via a reference impedance Zref, to the sense node; for each reference voltage, determining the value Imi of the current applied to the sense node; determining the sense reference voltage Vs to be provided to the sense node, which would lead to a current with an amplitude of zero; and calculating the unknown sense impedance Zx of the sense electrode, with reference to the sense reference voltage Vs, the periodic guard voltage Vg, and the reference impedance Zref.
Method for determining a sense impedance in a guard-sense capacitive sensor
2020-06-30
Patent
Electronic Resource
English
METHOD FOR DETERMINING A SENSE IMPEDANCE IN A GUARD-SENSE CAPACITIVE SENSOR
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