Capacitive sensing system able of using heating element as antenna electrode

Combined heating and capacitive sensing system, comprising

• a heating element for producing heat when electrical current is caused to flow across it,
• a heating current supply having a first terminal connected to a first terminal of said heating element and a second terminal connected to a second terminal of said heating element so as to form a heating circuit,
• a capacitive detector connected to said heating element, configured for driving an alternating current into said heating element and for producing an output indicative of capacitance based upon said alternating current;
• a common mode choke having a first winding connected between said first terminal of said heating element and said first terminal of said heating current supply and a second winding connected between said second terminal of said heating element and said second terminal of said heating current supply, said common mode choke essentially preventing said alternating current from flowing from said heating element to said heating current supply;
• wherein said common mode choke comprises a third winding connected in parallel of at least one of said first and second windings, said capacitive detector being further configured for measuring a portion of said alternating current flowing across said third winding and for taking into account said measured portion of alternating current when producing said output.