IMPEDANCE CHANGE DETECTION IN WIRELESS POWER TRANSMISSION

• US 20100217553A1
• Filed: 12/17/2009
• Published: 08/26/2010
• Est. Priority Date: 01/22/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Rimini, Roberto, Lee, Kevin D., Von Novak, William, Toncich, Stanley S.
• Granted Patent: US 9,136,914 B2
• Time in Patent Office: Days
• US Class Current: 702/65
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: H02J 50/12 of the resonant type
• 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: H04B 5/0056 for use in interrogation, identification or read/write systems record carriers G06K7/00, G06K19/00; for railways B61L3/12
• CPC Class Codes: H04B 5/77 for interrogation

Abstract

Exemplary embodiments are directed to wireless power transfer. Energy from a transmit antenna is coupled to internal signals on a transmitter. An impedance measurement circuit generates an impedance indication signal for indicating an impedance difference between the coupled internal signals by comparing them. A controller samples the impedance indication signal and determines digital signaling values responsive to changes in the impedance indication signal. The impedance measurement circuit measures one or more of magnitude difference of the internal signals, phase difference of the internal signals, and changes in power consumed by an amplifier coupled between the RF signal and the transmit antenna. A transmitter generates the electromagnetic field with a transmit antenna responsive to a Radio Frequency (RF) signal to create a coupling-mode region within a near field of the transmit antenna.

Claims

1. A method for detecting reverse-link signaling, comprising:

directionally coupling a forward link signal to a reverse link signal responsive to the forward link signal, wherein the forward link signal comprises an operable coupling of an RF signal input to a transmit signal output;

measuring an impedance difference between the forward link signal and the reverse link signal; and

determining digital signaling values responsive to changes in the impedance difference.

2. The method of claim 1, further comprising:

generating the RF signal input at a coupling frequency for a near field radiation; and

emitting the transmit signal output to generate a coupling-mode region of the near field radiation for coupling to a receive antenna on a receiver device.

3. The method of claim 1, wherein:

the measuring the impedance difference comprises;

determining a phase difference between the forward link signal and the reverse link signal; and

determining a magnitude difference between the forward link signal and the reverse link signal; and

the determining the digital signaling values is responsive to changes in the phase difference and changes in the magnitude difference.

4. The method of claim 3, wherein:

the measuring the impedance difference further comprises detecting changes in power consumed by an amplifier coupled between the RF signal input and the transmit signal output; and

the determining the digital signaling values is further responsive to the changes in power consumed by the amplifier.

5. The method of claim 4, further comprising:

determining a derivative of the phase difference, a derivate of the magnitude difference, and a derivative of the changes in power;

using a training sequence of data transitions to;

select one of the derivatives as a signal with the most power; and

compute an adaptive threshold for the signal with the most power; and

the determining the digital signaling values includes comparing subsequent data transitions to the adaptive threshold.

6. The method of claim 5, wherein using the training sequence to compute the adaptive threshold comprises:

summing values of a predetermined number of peaks of the training sequence for the signal with the most power;

determining an average tail value as an average value of the signal with the most power at temporal offsets after the predetermined number of peaks; and

averaging the sum of the predetermined number of peaks with the average tail value.

7. The method of claim 3, wherein the determining the digital signaling values comprises computing a distance comprising a square root of the sum of the square of the impedance difference and a square of the magnitude difference.

8. A wireless power transmitter, comprising:

a directional coupler having a forward link coupled between an RF signal input, and a transmit signal output and a reverse link coupled between a first port, and a second port;

an impedance measurement circuit with a first input operably coupled to the first port, a second input operably coupled to the second port, and for generating an impedance indication signal to indicate an impedance difference between the forward link and the reverse link; and

a controller for sampling the impedance indication signal and determining digital signaling values responsive to changes in the impedance indication signal.

9. The wireless power transmitter of claim 8, further comprising:

a transmit antenna for emitting the transmit signal output to generate a coupling-mode region of near field radiation for coupling to a receive antenna on a receiver device; and

an signal generator for generating the RF signal input at a coupling frequency of the near field radiation.

10. The wireless power transmitter of claim 8, wherein the impedance measurement circuit comprises:

a phase determiner with a first input operably coupled to the first port, a second input operably coupled to the second port, and a phase output for indicating a phase difference between the forward link and the reverse link; and

a magnitude determiner with a first input operably coupled to the first port, a second input operably coupled to the second port, and a magnitude output for indicating a magnitude difference between the forward link and the reverse link; and

wherein the controller is further for sampling the phase output and the magnitude output and determining the digital signaling values responsive to changes in the phase output and changes in the magnitude output.

11. The wireless power transmitter of claim 10, wherein the impedance measurement circuit further comprises:

an amplifier operably coupled between the signal generator and the directional coupler; and

a load sensing circuit operably coupled to the amplifier for detecting a change in power consumed by the amplifier; and

wherein the controller is further for sampling the change in power and including the change in power in determining the digital signaling values responsive to changes in the phase output and changes in the magnitude output.

12. The wireless power transmitter of claim 11, wherein the controller is further for:

determining a derivative of the phase output, a derivate of the magnitude output, and a derivative of the change in power;

using a training sequence of data transitions to;

select one of the derivatives as a signal with the most power; and

compute an adaptive threshold for the signal with the most power; and

determining the digital signaling values by comparing subsequent data transitions to the adaptive threshold.

13. The wireless power transmitter of claim 12, wherein the controller is further for computing the adaptive threshold by:

summing values of a predetermined number of peaks of the training sequence for the signal with the most power;

determining an average tail value as an average value of the signal with the most power at temporal offsets after the predetermined number of peaks; and

averaging the sum of the predetermined number of peaks with the average tail value.

14. The wireless power transmitter of claim 10, wherein the controller is further for determining the digital signaling values by computing a distance comprising a square root of the sum of the square of the impedance difference and a square of the magnitude difference.

15. An apparatus for detecting reverse-link signaling, comprising:

means for directionally coupling a forward link signal to a reverse link signal responsive to the forward link signal, wherein the forward link signal comprises an operable coupling of an RF signal input to a transmit signal output;

means for measuring an impedance difference between the forward link signal and the reverse link signal; and

means for determining digital signaling values responsive to changes in the impedance difference.

16. The apparatus of claim 15, further comprising:

means for generating the RF signal input at a coupling frequency for a near field radiation; and

means for emitting the transmit signal output to generate a coupling-mode region of the near field radiation for coupling to a receive antenna on a receiver device.

17. The apparatus of claim 15, wherein:

the means for measuring the impedance difference comprises;

means for determining a phase difference between the forward link signal and the reverse link signal; and

means for determining a magnitude difference between the forward link signal and the reverse link signal; and

the means for determining the digital signaling values is responsive to changes in the phase difference and changes in the magnitude difference.

18. The apparatus of claim 17, wherein:

the means for measuring the impedance difference further comprises means for detecting changes in power consumed by an amplifier coupled between the RF signal input and the transmit signal output; and

the means for determining the digital signaling values is further responsive to the changes in power consumed by the amplifier.

19. The apparatus of claim 18, further comprising:

means for determining a derivative of the phase difference, a derivate of the magnitude difference, and a derivative of the changes in power;

means for using a training sequence of data transitions to;

select one of the derivatives as a signal with the most power; and

compute an adaptive threshold for the signal with the most power; and

the means for determining the digital signaling values includes comparing subsequent data transitions to the adaptive threshold.

20. The apparatus of claim 19, wherein the means for using the training sequence to compute the adaptive threshold comprises:

means for summing values of a predetermined number of peaks of the training sequence for the signal with the most power;

means for determining an average tail value as an average value of the signal with the most power at temporal offsets after the predetermined number of peaks; and

means for averaging the sum of the predetermined number of peaks with the average tail value.

21. The apparatus of claim 17, wherein the means for determining the digital signaling values comprises means for computing a distance comprising a square root of the sum of the square of the impedance difference and a square of the magnitude difference.

22. A method for detecting reverse-link signaling, comprising:

coupling an RF signal input to a transmit signal output and non-directionally coupling a coupled port to the transmit signal output to generate a coupled output proportional to the transmit signal output;

generating a sensed voltage correlated to the coupled output;

measuring an impedance difference between the RF signal input and the sensed voltage; and

determining digital signaling values responsive to changes in the impedance difference.

23. The method of claim 22, further comprising:

generating the RF signal input at a coupling frequency for a near field radiation; and

emitting the transmit signal output to generate a coupling-mode region of the near field radiation for coupling to a receive antenna on a receiver device.

24. The method of claim 22, wherein:

the measuring the impedance difference comprises determining a phase difference between the RF signal input and the sensed voltage; and

the determining the digital signaling values is responsive to changes in the phase difference.

25. The method of claim 22, wherein:

the measuring the impedance difference comprises;

determining a phase difference between the RF signal input and the sensed voltage; and

determining a magnitude difference between the RF signal input and the sensed voltage; and

the determining the digital signaling values is responsive to changes in the phase difference and changes in the magnitude difference.

26. The method of claim 25, wherein:

the measuring the impedance difference further comprises detecting changes in power consumed by an amplifier coupled between the RF signal input and the transmit signal output; and

the determining the digital signaling values is further responsive to the changes in power consumed by the amplifier.

27. The method of claim 26, further comprising:

determining a derivative of the phase difference, a derivate of the magnitude difference, and a derivative of the changes in power;

using a training sequence of data transitions to;

select one of the derivatives as a signal with the most power; and

compute an adaptive threshold for the signal with the most power; and

the determining the digital signaling values includes comparing subsequent data transitions to the adaptive threshold.

28. The method of claim 27, wherein using the training sequence to compute the adaptive threshold comprises:

summing values of a predetermined number of peaks of the training sequence for the signal with the most power;

determining an average tail value as an average value of the signal with the most power at temporal offsets after the predetermined number of peaks; and

averaging the sum of the predetermined number of peaks with the average tail value.

29. The method of claim 25, wherein the determining the digital signaling values comprises computing a distance comprising a square root of the sum of the square of the impedance difference and a square of the magnitude difference.

30. A wireless power transmitter, comprising:

a non-directional coupler operably coupled between an RF signal input and a transmit signal output and including a coupled port for generating a coupled output proportional to the transmit signal output;

a reference circuit operably coupled between the coupled output and a ground for generating a sensed voltage correlated to an amplitude of the transmit signal output;

an impedance measurement circuit with a first input operably coupled to the RF signal input, a second input operably coupled to the sensed voltage, and an impedance indication signal for indicating an impedance difference between the RF signal input and the transmit signal output; and

a controller for sampling the impedance indication signal and determining digital signaling values responsive to changes in the impedance indication signal.

31. The wireless power transmitter of claim 30, further comprising:

a transmit antenna for emitting the transmit signal output to generate a coupling-mode region of near field radiation for coupling to a receive antenna on a receiver device; and

a signal generator for generating the RF signal input at a coupling frequency of the near field radiation.

32. The wireless power transmitter of claim 30, wherein:

the impedance measurement circuit comprises a phase determiner with a first input operably coupled to the RF signal input, a second input operably coupled to the sensed voltage, and a phase output for indicating a phase difference between the RF signal input and the sensed voltage; and

the controller is further for sampling the phase output and determining the digital signaling values responsive to changes in the phase output.

33. The wireless power transmitter of claim 30, wherein the impedance measurement circuit comprises:

a phase determiner with a first input operably coupled to the RF signal input, a second input operably coupled to the sensed voltage, and a phase output for indicating a phase difference between the RF signal input and the sensed voltage; and

a magnitude determiner with a first input operably coupled to the RF signal input, a second input operably coupled to the sensed voltage, and a magnitude output for indicating a magnitude difference between the RF signal input and the sensed voltage; and

wherein the controller is further for sampling the phase output and the magnitude output and determining the digital signaling values responsive to changes in the phase output and changes in the magnitude output.

34. The wireless power transmitter of claim 33, wherein the impedance measurement circuit further comprises:

an amplifier operably coupled between the signal generator and the directional coupler; and

a load sensing circuit operably coupled to the amplifier for detecting a change in power consumed by the amplifier; and

wherein the controller is further for sampling the change in power and including the change in power in determining the digital signaling values responsive to changes in the phase output and changes in the magnitude output.

35. The wireless power transmitter of claim 34, wherein the controller is further for:

determining a derivative of the phase output, a derivate of the magnitude output, and a derivative of the change in power;

using a training sequence of data transitions to;

select one of the derivatives as a signal with the most power; and

compute an adaptive threshold for the signal with the most power; and

determining the digital signaling values by comparing subsequent data transitions to the adaptive threshold.

36. The wireless power transmitter of claim 35, wherein the controller is further for computing the adaptive threshold by:

summing values of a predetermined number of peaks of the training sequence for the signal with the most power;

determining an average tail value as an average value of the signal with the most power at temporal offsets after the predetermined number of peaks; and

averaging the sum of the predetermined number of peaks with the average tail value.

37. The wireless power transmitter of claim 33, wherein the controller is further for determining the digital signaling values by computing a distance comprising a square root of the sum of the square of the impedance difference and a square of the magnitude difference.

38. An apparatus for detecting reverse-link signaling, comprising:

means for coupling an RF signal input to a transmit signal output and non-directionally coupling a coupled port to the transmit signal output to generate a coupled output proportional to the transmit signal output;

means for generating a sensed voltage correlated to the coupled output;

means for measuring an impedance difference between the RF signal input and the sensed voltage; and

means for determining digital signaling values responsive to changes in the impedance difference.

39. The apparatus of claim 38, further comprising:

means for generating the RF signal input at a coupling frequency for a near field radiation; and

means for emitting the transmit signal output to generate a coupling-mode region of the near field radiation for coupling to a receive antenna on a receiver device.

40. The apparatus of claim 38, wherein:

the means for measuring the impedance difference comprises determining a phase difference between the RF signal input and the sensed voltage; and

the means for determining the digital signaling values is responsive to changes in the phase difference.

41. The apparatus of claim 38, wherein:

the means for measuring the impedance difference comprises;

means for determining a phase difference between the RF signal input and the sensed voltage; and

means for determining a magnitude difference between the RF signal input and the sensed voltage; and

the means for determining the digital signaling values is responsive to changes in the phase difference and changes in the magnitude difference.

42. The apparatus of claim 41, wherein:

the means for measuring the impedance difference further comprises means for detecting changes in power consumed by an amplifier coupled between the RF signal input and the transmit signal output; and

the means for determining the digital signaling values is further responsive to the changes in power consumed by the amplifier.

43. The apparatus of claim 42, further comprising:

means for determining a derivative of the phase difference, a derivate of the magnitude difference, and a derivative of the changes in power;

means for using a training sequence of data transitions to;

select one of the derivatives as a signal with the most power; and

compute an adaptive threshold for the signal with the most power; and

the means for determining the digital signaling values includes comparing subsequent data transitions to the adaptive threshold.

44. The apparatus of claim 43, wherein the means for using the training sequence to compute the adaptive threshold comprises:

means for summing values of a predetermined number of peaks of the training sequence for the signal with the most power;

means for determining an average tail value as an average value of the signal with the most power at temporal offsets after the predetermined number of peaks; and

means for averaging the sum of the predetermined number of peaks with the average tail value.

45. The apparatus of claim 41, wherein the means for determining the digital signaling values comprises means for computing a distance comprising a square root of the sum of the square of the impedance difference and a square of the magnitude difference.