All-in-one method for wireless connectivity and contactless battery charging of small wearables

1. A wearable device comprising:

a battery;

an antenna coil;

a wireless charging module coupled to the antenna coil to harvest wireless power for charging the battery;

an NFC (near field communications) module coupled to the antenna coil to receive a query signal and provide a tag response signal;

an NFMI (near field magnetic induction) module coupled to the antenna coil to send and receive audio streams;

a controller; and

an adjustable capacitance in series or parallel with said antenna coil to provide a tunable resonant frequency, wherein the controller adjusts the resonant frequency to a value suitable for a selected one of said wireless charging, NFC, and NFMI modules.

2. The device of claim 1 , further comprising a microphone and speaker, wherein the device operates as a hearing aid.

3. The device of claim 2 , wherein said audio streams are exchanged by said hearing aid in a first ear of a user with a second hearing aid in a second, opposite ear of said user.

4. The device of claim 2 , wherein the NFC module further reports parameter values and accepts new parameter values for operation as said hearing aid.

5. The device of claim 1 , wherein the antenna coil comprises a ferrite element.

6. The device of claim 1 , wherein the controller selectively enables one of said wireless charging, NFC, and NFMI modules at a time.

7. The device of claim 6 , wherein the controller systematically cycles through each resonant frequency value for said wireless charging, NFC, and NFMI modules.

8. The device of claim 1 , wherein the controller monitors charging of the battery when the wireless charging module is selected and, upon detecting an overvoltage, the controller adjusts the capacitance to detune the antenna coil to a different resonant frequency that protects against the overvoltage.

9. The device of claim 1 , wherein the adjustable capacitance is in parallel with said antenna coil.

10. The device of claim 1 , wherein the adjustable capacitance is in series with said antenna coil.

11. A wireless communication method that comprises:

coupling an antenna coil to a wireless charging module to charge a battery;

coupling the antenna coil to an NFC (near field communications) module, the NFC module:

receiving a query signal;

providing a tag response signal; and

receiving a command signal to set at least one parameter value affecting rendering of an audio stream;

coupling the antenna coil to an NFMI (near field magnetic induction) module to send or receive the audio stream; and

adjusting a capacitance in series or parallel with said antenna coil to tune a resonant frequency to a value suitable for a selected one of said wireless charging, NFC, and NFMI modules.

12. The method of claim 11 , further comprising: rendering the audio stream via a speaker in a hearing aid.

13. The method of claim 12 , wherein said audio stream is exchanged by said hearing aid in a first ear of a user with a second hearing aid in a second, opposite ear of said user.

14. The method of claim 12 , wherein the NFC module further reports parameter values and accepts new parameter values for operation of said hearing aid.

15. The method of claim 11 , wherein the antenna coil comprises a ferrite element.

16. The method of claim 11 , wherein said couplings are performed selectively, one at a time, by a controller.

17. The method of claim 16 , wherein the controller systematically cycles through each resonant frequency value for said wireless charging, NFC, and NFMI modules.

18. The method of claim 11 , further comprising monitoring charging of the battery when the wireless charging module is selected and, upon detecting an overvoltage, varying the capacitance to detune the antenna coil to a different resonant frequency that protects against the overvoltage.

19. A hearing aid that comprises:

a microphone;

a speaker;

a battery;

an antenna coil around a ferrite element;

a controller powered by the battery, wherein the controller filters and amplifies sound received via the microphone for playback via the speaker, and wherein the controller includes:

a wireless charging module coupled to the antenna coil to harvest wireless power for charging the battery;

an NFC (near field communications) module coupled to the antenna coil to receive a query signal and provide a tag response signal, wherein the NFC module further reports parameter values and accepts new parameter values for operation as said hearing aid; and

an NFMI (near field magnetic induction) module coupled to the antenna coil to exchange audio streams with a second hearing aid in an opposite ear,

wherein the controller selectively enables only one of the wireless charging, NFC, and NFMI modules at a time by setting an adjustable capacitance in series or parallel with said antenna coil to provide a tunable resonant frequency, wherein the controller adjusts the resonant frequency to a value suitable for the selected one of said wireless charging, NFC, and NFMI modules.