Seat heater and capacitive occupancy sensor combination

A combined seat heater and capacitive occupancy sensor comprises a heater network and a capacitive sensing network. The heater network includes a heating element (10) connected between a first node (21) and a second node (22) to dissipate heat. The capacitive sensing network is connected to the heating element to apply an oscillating voltage thereto and to derive a capacitive load of the heating element. The heater network comprises a common mode choke (16) connecting the first (21) and the second node (22) to a third (23) and a fourth (24) node, respectively. The capacitive sensing network further comprises means to sustain an oscillating signal in or to drive an oscillating signal into the heating element as well as a high-impedance amplifier (32) having an input node operatively connected to the heating element to probe the oscillating signal, and an output node (44) to provide an output signal indicative of the oscillating signal.