De-tuning in wireless power reception

• US 8,374,545 B2
• Filed: 05/11/2010
• Issued: 02/12/2013
• Est. Priority Date: 09/02/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Menegoli, Paolo, Irish, Linda S
• Primary Examiner(s): Trinh, Sonny
• Application Number:
  US12/778,028
• Publication Number:
  US 20110053500A1
• Time in Patent Office: 1,008 Days
• Field of Search: 455/41.1, 455/41.2, 455/572, 455/373, 455/343.1, 455/573, 307/104, 307/107
• 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 for operating a receiver, comprising:

generating an RF signal based on power wirelessly received;

providing a control signal to a variable impedance device configured to modify the RF signal, the control signal having a voltage level, the variable impedance device configured to conduct a current that is proportional to the voltage level;

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

generating another control signal based on a voltage difference between the DC signal and a reference voltage.

2. The method of claim 1, wherein the providing a control signal to a variable impedance device configured to modify the RF signal further comprises providing the control signal to an NMOS transistor configured to operate in a linear region.

3. The method of claim 1, wherein the providing a control signal to a variable impedance device configured to modify 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 another control signal or selecting linear de-tuning by selecting a result from the comparing the DC signal to the reference voltage to generate the another 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 generating an RF signal based on power wirelessly received;

means for providing a control signal to a variable impedance device configured to modify the RF signal, the control signal having a voltage level, the variable impedance device configured to conduct a current that is proportional to the voltage level;

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

means for generating another control signal based on a voltage difference between the DC signal and a reference voltage.

7. The wireless power receiver of claim 6, wherein the providing a control signal to a variable impedance device configured to modify the RF signal further comprises means for providing the control signal to an NMOS transistor configured to operate in a linear region.

8. The wireless power receiver of claim 6, wherein the means for providing a control signal to a variable impedance device configured to modify 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 another control signal or selecting linear de-tuning by selecting a result from the comparing the DC signal to the reference voltage to generate the another 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 coupled to a receive antenna, the matching circuit and the receive antenna configured to generate an RF signal based on power wirelessly received;

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

a rectifier operably coupled to the modified RF signal and configured to convert 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 variable impedance device and configured to generate another control signal based on 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 comparator output.

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 comparator output.

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 variable impedance device.

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

a buffer operably coupled between the OTA output and the variable impedance device.

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 variable impedance device, 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 to generate 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 to rectify the modulated signal to a receive signal.

19. A method for detecting a signal from a transmitter, comprising:

generating an RF signal based on power wirelessly received;

modifying, by a de-tuning circuit, a frequency of the RF signal to a frequency different from a 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 modifying, by a de-tuning circuit, a frequency of the RF signal to a frequency different from a resonant frequency further comprises adjusting a variable impedance of the de-tuning circuit based on 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 of the modified RF signal substantially less than an amplitude of the RF signal.

23. A wireless power receiver, comprising:

means for generating an RF signal based on power wirelessly received;

means for modifying, by a de-tuning circuit, a frequency of the RF signal to a frequency different from a 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 means for modifying, by a de-tuning circuit, a frequency of the RF signal to a frequency different from a resonant frequency 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 do-tuned from the resonant frequency to a different frequency, and partially de-tuned with an amplitude of for the modified RF signal substantially less than an amplitude of the RF signal.

27. A wireless power receiver, comprising:

a matching circuit coupled to a receive antenna, the matching circuit and the receive antenna configured to generate an RF signal at a resonant frequency based on power wirelessly received;

a de-tuning circuit operably coupled to the matching circuit and configured to modify 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 to generate 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 to rectify 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 and configured to receive a control signal, the variable impedance device configured to generate a modified RF signal with resonance characteristics different from the RF signal based on the control 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 of the modified RF signal substantially less than an amplitude of the RF signal.