DE-TUNING IN WIRELESS POWER RECEPTION

• US 20110053500A1
• Filed: 05/11/2010
• Published: 03/03/2011
• Est. Priority Date: 09/02/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Irish, Linda S., Menegoli, Paolo
• Granted Patent: US 8,374,545 B2
• Time in Patent Office: Days
• US Class Current: 455/41.1
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/0047 with monitoring or indicating devices or circuits
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

Exemplary embodiments are directed to wireless power transfer. A receiver with a receive antenna couples with near field radiation in a coupling-mode region. The receiver generates an RF signal at a resonant frequency responsive to the near field radiation. A de-tuning circuit generates a variable impedance responsive to a control signal to modify the RF signal to a smaller amplitude or to a different resonant frequency. A rectifier converts the modified RF signal to a DC signal. A comparator creates a feedback loop by generating the control signal responsive to comparing the DC signal to a reference voltage. The de-tuning circuit may operate in digital mode or in linear mode with the feedback. An impedance element may be coupled to the de-tuning circuit to generate a voltage proportional to a current through the de-tuning circuit. The proportional voltage is rectified to a receive signal with information sent from a transmitter.

Claims

1. A method, comprising:

coupling near field radiation at a resonant frequency in a coupling-mode region to generate an RF signal responsive to the near field radiation;

de-tuning the RF signal with a variable impedance device responsive to a control signal to modify the RF signal;

rectifying the modified RF signal to generate a DC signal; and

comparing the DC signal to a reference voltage to generate the control signal responsive to a voltage difference between the DC signal and the reference voltage.

2. The method of claim 1, wherein the de-tuning the RF signal further comprises operating an NMOS transistor in a linear region responsive to the control signal.

3. The method of claim 1, wherein the de-tuning the RF signal further comprises providing a reactive component to the variable impedance device with a capacitor operably coupled to the variable impedance device.

4. The method of claim 1, further comprising selecting digital de-tuning by selecting a digital cloaking signal to generate the control signal or selecting linear de-tuning by selecting a result from the comparing the DC signal to the reference voltage to generate the control signal.

5. The method of claim 1, further comprising:

generating a modulated signal with a voltage proportional to a current through the variable impedance device; and

rectifying a receive signal from the modulated signal.

6. A wireless power receiver, comprising:

means for coupling near field radiation at a resonant frequency in a coupling-mode region to generate an RF signal responsive to the near field radiation;

means for de-tuning the RF signal with a variable impedance device responsive to a control signal to modify the RF signal;

means for rectifying the modified RF signal to generate a DC signal; and

means for comparing the DC signal to a reference voltage to generate the control signal responsive to a voltage difference between the DC signal and the reference voltage.

7. The wireless power receiver of claim 6, wherein the means for de-tuning the RF signal further comprises means for operating an NMOS transistor in a linear region responsive to the control signal.

8. The wireless power receiver of claim 6, wherein the means for de-tuning the RF signal further comprises means for coupling a reactive component to the variable impedance device.

9. The wireless power receiver of claim 6, further comprising means for selecting digital de-tuning by selecting a digital cloaking signal to generate the control signal or selecting linear de-tuning by selecting a result from the comparing the DC signal to the reference voltage to generate the control signal.

10. The wireless power receiver of claim 6, further comprising:

means for generating a modulated signal with a voltage proportional to a current through the variable impedance device; and

means for rectifying a receive signal from the modulated signal.

11. A wireless power receiver, comprising:

a matching circuit for operable coupling to a receive antenna configured for coupling with near field radiation in a coupling-mode region, the matching circuit and the receive antenna for generating an RF signal responsive to the near field radiation;

a de-tuning circuit operably coupled to the matching circuit and comprising a variable impedance device with a variable resistance responsive to a control signal to modify the RF signal;

a rectifier operably coupled to the modified RF signal and configured for converting the modified RF signal to a DC signal; and

an analog comparator comprising a first input operably coupled to the DC signal, a second input operably coupled to a reference voltage, and a comparator output operably coupled to the control signal and configured to correspond to a voltage difference between the first input and the second input.

12. The wireless power receiver of claim 11, wherein the variable impedance device comprises an NMOS transistor with a source and drain operably coupled between a ground and the RF signal and a gate operably coupled to the control signal.

13. The wireless power receiver of claim 11, wherein the variable impedance device comprises back-to-back NMOS transistors operably coupled between a ground and the RF signal and gates of the gate back-to-back NMOS transistors operably coupled to the control signal.

14. The wireless power receiver of claim 11, wherein the de-tuning circuit further comprises a passive network operably coupled between the variable impedance device and the RF signal, the passive network configured for providing a reactive component to an impedance of the de-tuning circuit.

15. The wireless power receiver of claim 11, wherein the analog comparator comprises:

a voltage divider for providing a comparison signal proportional to the DC signal; and

an amplifier with one input operably coupled to the comparison signal, another input operably coupled to the reference voltage, and an output operably coupled to the control signal.

16. The wireless power receiver of claim 11, wherein the analog comparator comprises:

an operational transconductance amplifier (OTA) with one input operably coupled to the DC signal and another input operably coupled to the reference voltage to generate an OTA output; and

and a buffer operably coupled between the OTA output and the control signal.

17. The wireless power receiver of claim 11, further comprising a multiplexer operably coupled between the analog comparator and the de-tuning circuit with one input operably coupled to the comparator output, one input operably coupled to a digital cloaking signal, and an output operably coupled to the control signal, wherein the multiplexer is configured to select digital de-tuning by selecting the digital cloaking signal or linear de-tuning by selecting the comparator output.

18. The wireless power receiver of claim 11, further comprising a signaling sensor comprising:

an impedance element operably coupled between the de-tuning circuit and the ground and configured for generating a modulated signal with a voltage proportional to a current through the variable impedance device; and

a signal extractor operably coupled to the modulated signal and configured for rectifying the modulated signal to a receive signal.

19. A method, comprising:

coupling near field radiation at a resonant frequency in a coupling-mode region to generate an RF signal responsive to the near field radiation;

de-tuning the RF signal using a de-tuning circuit to modify a frequency of the RF signal to a frequency different from the resonant frequency;

generating a modulated signal with a voltage proportional to a current through the de-tuning circuit; and

rectifying the modulated signal to a receive signal, the receive signal responsive to a tuned state of the RF signal.

20. The method of claim 19, wherein the tuned state of the RF signal comprises substantially tuned to the resonant frequency or substantially de-tuned from the resonant frequency to a different frequency.

21. The method of claim 19, wherein de-tuning the RF signal further comprises adjusting a variable impedance of the de-tuning circuit responsive to a control signal to modify the RF signal with resonance characteristics different from the RF signal.

22. The method of claim 21, wherein the tuned state of the RF signal comprises substantially tuned to the resonant frequency, substantially de-tuned from the resonant frequency to a different frequency, and partially de-tuned with an amplitude for the modified RF signal substantially less than an amplitude of the RF signal.

23. A wireless power receiver, comprising:

means for coupling near field radiation at a resonant frequency in a coupling-mode region to generate an RF signal responsive to the near field radiation;

means for de-tuning the RF signal using a de-tuning circuit to modify a frequency of the RF signal to a frequency different from the resonant frequency;

means for generating a modulated signal with a voltage proportional to a current through the de-tuning circuit; and

means for rectifying the modulated signal to a receive signal, the receive signal responsive to a tuned state of the RF signal.

24. The wireless power receiver of claim 23, wherein the tuned state of the RF signal comprises substantially tuned to the resonant frequency or substantially de-tuned from the resonant frequency to a different frequency.

25. The wireless power receiver of claim 23, wherein de-tuning the RF signal further comprises means for adjusting a variable impedance of the de-tuning circuit responsive to a control signal to modify the RF signal with resonance characteristics different from the RF signal.

26. The wireless power receiver of claim 25, wherein the tuned state of the RF signal comprises substantially tuned to the resonant frequency, substantially de-tuned from the resonant frequency to a different frequency, and partially de-tuned with an amplitude for the modified RF signal substantially less than an amplitude of the RF signal.

27. A wireless power receiver, comprising:

a matching circuit for operable coupling to a receive antenna configured for coupling with near field radiation in a coupling-mode region, the matching circuit and the receive antenna for generating an RF signal at a resonant frequency responsive to the near field radiation;

a de-tuning circuit operably coupled to the matching circuit and configured for modifying a tuning of the wireless power receiver to a frequency different from the resonant frequency of the RF signal;

an impedance element operably coupled between the de-tuning circuit and a ground and configured for generating a modulated signal with a voltage proportional to a current through the de-tuning circuit; and

a signal extractor operably coupled to the modulated signal and configured for rectifying the modulated signal to a receive signal responsive to a tuned state of the wireless power receiver.

28. The wireless power receiver of claim 27, wherein the tuned state of the wireless power receiver comprises substantially tuned to the resonant frequency or substantially de-tuned from the resonant frequency to a different frequency.

29. The wireless power receiver of claim 27, wherein the de-tuning circuit further comprises a variable impedance device operably coupled between the RF signal and the impedance element, the variable impedance device comprising a variable resistance responsive to a control signal to generate a modified RF signal with resonance characteristics different from the RF signal.

30. The wireless power receiver of claim 29, wherein the tuned state of the wireless power receiver comprises substantially tuned to the resonant frequency, substantially de-tuned from the resonant frequency to a different frequency, and partially de-tuned with an amplitude for the modified RF signal substantially less than an amplitude of the RF signal.