An impedance measurement circuit for determining a complex impedance of a capacitive sensor that is configured for employing at least one electric heater member as an electrode to be operated in loading mode. The measurement circuit includes: a signal generating unit for providing an electric measurement signal; a signal sensing circuit measuring current through the at least one electric heater member; an electric heater member connection circuit comprising a plurality of MOSFETs for selectively electrically connecting the electric heater member either to the signal sensing circuit for complex impedance measurement or to a DC electric power unit for heating purposes; and a control and evaluation unit that is configured for controlling a switching status of the plurality of MOSFETs according to a predefined sequence, and for determining a complex impedance from the determined currents with reference to a complex reference potential during predefined stages of the predefined sequence.
LOW-COST, PROTECTED CAPACITIVE SENSING CIRCUIT FOR LOADING MODE OPERATION OF CAPACITIVE SENSORS EMPLOYING HEATER MEMBERS
2024-08-15
Patent
Electronic Resource
English
European Patent Office | 2024
|European Patent Office | 2022
|European Patent Office | 2024
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