Apple Inc.
Common mode noise compensation in wireless power systems

Abstract:

Disclosed are devices, systems, and methods for reducing common mode noise induced in wireless charging circuits of electronic devices. For an electronic device having an inductive receiving coil near an electric shielding layer, differences in parasitic capacitances of the loops of the inductive receiving coil with an electric shielding layer can induce common mode noise. Common mode noise is reduced by a noise-reduction capacitor from the inductive receiving coil to the electric shielding layer together with a grounding resistor from the electric shielding layer to a common ground of the wireless charging circuit.