An electronic device includes a depth sensor and an inertial measurement unit. The electronic device detects a presence of the user of the electronic device by analyzing a combination of inertial sensor signals from the inertial measurement unit and depth sensor signals from the depth sensor.

A system and method generate an alternating current (AC) input signal by a digitally controlled resonant drive circuit. The method includes driving a face tracking sensor with the input signal. An output signal is received from the face tracking sensor and an amplitude of the output signal is…