Common Mode Noise Compensation in Wireless Power Systems
AssigneeApple Inc.
InventorsWeihong Qiu, Rohan Dayal, Zaki Moussaoui
Life of this patent
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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.
Claims20
An electronic device, comprising:
- a housing;
- a receive coil comprising an electrode;
- an electric shielding layer disposed between the receive coil and the housing;
- a noise-reduction capacitor connected coupled to the electrode at a circuit node and coupled to the electric shielding layer;
- and
- a grounding resistor connecting the electric shielding layer to a common ground.
A method of reducing noise in wireless charging circuitry of an electronic device, the method comprising:
- shielding the wireless charging circuitry with an electric shielding layer positioned between the wireless charging circuitry and an exterior surface of the electronic device;
- connecting a resistor from the electric shielding layer to a common ground of the electronic device;
- and
- coupling a noise-reduction capacitor in series from an electrode of the receive coil to the electric shielding layer of the electronic device.
A system of wireless transmission of power to an electronic device, comprising:
- a power transmitter comprising:
- an exterior surface;
- a transmit coil;
- and
- a transmit-side electric shielding layer positioned between the exterior surface and the transmit coil;
- and
- a power receiver within the electronic device comprising:
- a receive coil comprising a first electrode;
- a receive-side electric shielding layer positioned between the receive coil and a housing of the electronic device;
- a noise-reduction capacitor coupling the electrode to the receive-side electric shielding layer;
- and
- a grounding resistor connected from the receive-side electric shielding layer to a common ground of the electronic device;
- wherein:
- the noise-reduction capacitor and the grounding resistor are operable to attenuate common mode noise.
Dependencies are inferred from the claim text.