Method for wireless charging power control

1. A method for wireless charging power control comprising:

determining an effective charging power in a direct-current (DC) charging signal that charges a battery, wherein the DC charging signal is generated by a radio frequency (RF) power harvesting circuit to have the effective charging power proportional to a total RF power received in a wireless RF charging signal received from a wireless charging station;

generating a battery charging signal indication (BCSI) in response to:

determining a target charging power required by the battery based on a charging profile of the battery;

comparing the effective charging power against the target charging power required by the battery; and

the determined effective charging power in the DC charging signal being different from the target charging power without adjusting the effective charging power in the DC charging signal by adjusting settings of the RF power harvesting circuit; and

sending the BCSI to the wireless charging station to control the total RF power associated with the RF wireless charging signal, wherein the BCSI is sent to the wireless charging station via an antenna switch configured to couple an antenna to the RF power harvesting circuit and one of a plurality of RF paths configured to transmit the BCSI on various RF spectrums of an Industrial, Scientific, and Medical (ISM) band.

2. The method of claim 1 further comprising receiving the wireless RF charging signal from the wireless charging station on an ISM band.

3. The method of claim 1 further comprising receiving the wireless RF charging signal from the wireless charging station and providing the BCSI to the wireless charging station by sharing at least one antenna.

4. The method of claim 1 further comprising receiving the wireless RF charging signal beamformed by the wireless charging station.

5. The method of claim 1 further comprising providing a training signal to the wireless charging station for beamforming the wireless RF charging signal.

6. The method of claim 1 further comprising providing the BCSI to the wireless charging station according to a predefined feedback schedule.

7. The method of claim 1 , further comprising:

sending the BCSI to the wireless charging station to decrease the total RF power associated with the wireless RF charging signal if the effective charging power is greater than the target charging power; and

sending the BCSI to the wireless charging station to increase the total RF power associated with the wireless RF charging signal if the effective charging power is less than the target charging power.

8. The method of claim 7 further comprising determining the target charging power required by the battery according to a lithium-ion (Li-ion) battery charging profile.

9. The method of claim 7 further comprising:

controlling at least one of a load-line impedance and the DC charging signal in the RF power harvesting circuit to decrease the effective charging power if the effective charging power is greater than the target charging power; and

controlling the at least one of the load-line impedance and the DC charging signal in the RF power harvesting circuit to increase the effective charging power if the effective charging power is less than the target charging power.

10. A method for wireless charging power control comprising:

comparing an effective charging power in a direct-current (DC) charging signal, which is generated by a radio frequency (RF) power harvesting circuit to charge a battery based on a total RF power in a wireless RF charging signal received from a wireless charging station, against a target charging power required by the battery;

reducing the effective charging power in the DC charging signal generated by the RF power harvesting circuit without sending a battery charging signal indication (BCSI) to the wireless charging station to decrease the total RF power associated with the wireless RF charging signal if the effective charging power is greater than the target charging power, wherein the BCSI is configured to be sent to the wireless charging station via an antenna switch configured to couple an antenna to the RF power harvesting circuit and one of a plurality of RF paths configured to transmit the BCSI on various RF spectrums of an Industrial, Scientific, and Medical (ISM) band; and

increasing the effective charging power in the DC charging signal generated by the RF power harvesting circuit independent of sending the BCSI to the wireless charging station to increase the total RF power associated with the wireless RF charging signal if the effective charging power is less than the target charging power.

11. The method of claim 10 further comprising controlling the RF power harvesting circuit based on instructions received from the wireless charging station.

12. The method of claim 10 further comprising adjusting a load-line impedance of the RF power harvesting circuit to mismatch an input impedance of the RF power harvesting circuit if the effective charging power is greater than the target charging power of the battery.

13. The method of claim 10 further comprising adjusting a load-line impedance of the RF power harvesting circuit to be substantially higher than an input impedance of the RF power harvesting circuit if the effective charging power is less than the target charging power of the battery.

14. The method of claim 10 further comprising decreasing duty-cycle of the DC charging signal if the effective charging power is greater than the target charging power of the battery.

15. The method of claim 10 further comprising increasing duty-cycle of the DC charging signal if the effective charging power is less than the target charging power of the battery.

16. The method of claim 10 further comprising adjusting a load-line impedance of the RF power harvesting circuit to mismatch an input impedance of the RF power harvesting circuit and decreasing duty-cycle of the DC charging signal if the effective charging power is greater than the target charging power of the battery.

17. The method of claim 10 further comprising adjusting a load-line impedance of the RF power harvesting circuit to be substantially higher than an input impedance of the RF power harvesting circuit and increasing duty-cycle of the DC charging signal.

18. The method of claim 10 further comprising determining the target charging power required by the battery according to a battery charging profile.