Methods and apparatus for improving remote NFC device detection using a low power oscillator circuit

• US 9,698,872 B2
• Filed: 06/18/2013
• Issued: 07/04/2017
• Est. Priority Date: 06/18/2013
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Brockenbrough, Roger, Reynolds, Todd, Haverinen, Anssi Kaleva, Wong, Angelica, Lee, Sang-Min
• Primary Examiner(s): Lu, Zhiyu
• Application Number:
  US13/920,670
• Publication Number:
  US 20140370803A1
• Time in Patent Office: 1,477 Days
• Field of Search: None
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 5/72 for local intradevice communication
• CPC Class Codes: H04B 5/77 for interrogation
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method, an apparatus, and a computer program product for inductive communication are provided in connection with providing mechanisms for detecting a remote NFC device without excessive power consumption. In one example, a communications device is equipped to monitor frequency oscillations associated with a NFC antenna using a calibrated LPO, determine that a number of occurrences of the frequency oscillations from a reference frequency is greater than a frequency deviation threshold, and perform a NFC polling procedure in response to the determination.

Claims

1. A method of wireless communications, comprising:

monitoring frequency oscillations associated with a near field communication (NFC) antenna and a matching network using a calibrated low power oscillator (LPO) connected to the NFC antenna, wherein the monitoring comprises;

generating the frequency oscillations using the LPO; and

counting a number of occurrences of the frequency oscillations using a frequency counter connected to the LPO, wherein the frequency oscillations are at a frequency which is a function of an impedance of the NFC antenna;

determining that the number of occurrences of the frequency oscillations is greater than a frequency deviation threshold from a reference frequency;

waking up an NFC chip and a crystal oscillator coupled to the NFC antenna and matching network in response to the determination; and

performing a NFC polling procedure using the NFC chip and the crystal oscillator to determine whether the frequency deviation is based on the presence of a remote NFC device in response to the determination.

2. The method of claim 1, further comprising:

calibrating the LPO using the crystal oscillator, wherein the crystal oscillator provides a comparatively higher quality reference clock value to a reference clock value associated with the LPO.

3. The method of claim 2, wherein the calibration is performed periodically.

4. The method of claim 2, wherein the calibration is performed when a subsystem that uses the crystal oscillator is activated.

5. The method of claim 2, wherein the calibration is performed once per an integer number of wake-up cycles, wherein the integer is greater than one.

6. The method of claim 1, wherein the monitoring is performed continuously.

7. The method of claim 1, wherein the number of occurrences is averaged over a time duration.

8. The method of claim 1, wherein the reference frequency is adaptively determined based on one or more previously determined values.

9. The method of claim 1, wherein the number of occurrences of the frequency oscillations is based on changes in impedance associated with the NFC antenna.

10. An apparatus for wireless communications, comprising:

means for monitoring frequency oscillations associated with a near field communication (NFC) antenna and a matching network using a calibrated low power oscillator (LPO) connected to the NFC antenna, wherein the means for monitoring are further configured to;

generate the frequency oscillations using the LPO connected to the NFC antenna; and

count a number of occurrences of occurrences of the frequency oscillations using a frequency counter connected to the LPO, wherein the frequency oscillations are at a frequency which is a function of an impedance of the NFC antenna;

means for determining that the number of occurrences of the frequency oscillations is greater than a frequency deviation threshold from a reference frequency;

means for waking up an NFC chip and a crystal oscillator coupled to the NFC antenna and matching network in response to the determination; and

means for performing a NFC polling procedure using the NFC chip and the crystal oscillator to determine whether the frequency deviation is based on the presence of a remote NFC device in response to the determination.

11. The apparatus of claim 10, further comprising:

means for calibrating the LPO using the crystal oscillator, wherein the crystal oscillator provides a comparatively higher quality reference clock value to a reference clock value associated with the LPO.

12. The apparatus of claim 11, wherein the calibration is performed periodically.

13. The apparatus of claim 11, wherein the calibration is performed when a subsystem that uses the crystal oscillator is activated.

14. The apparatus of claim 11, wherein the calibration is performed once per an integer number of wake-up cycles, wherein the integer is greater than one.

15. The apparatus of claim 10, wherein the monitoring is performed continuously.

16. The apparatus of claim 10, wherein the number of occurrences is averaged over a time duration.

17. The apparatus of claim 10, wherein the reference frequency is adaptively determined based on one or more previously determined values.

18. The apparatus of claim 10, wherein the number of occurrences of the frequency oscillations is based on changes in impedance associated with the NFC antenna.

19. A non-transitory computer-readable medium comprising code for:

monitoring frequency oscillations associated with a near field communication (NFC) antenna and a matching network using a calibrated low power oscillator (LPO) connected to the NFC antenna, wherein the code for monitoring the frequency oscillations comprises code for;

generating the frequency oscillations using the LPO coupled to the NFC antenna; and

counting a number of occurrences of the frequency oscillations using a frequency counter connected to the LPO, wherein the frequency oscillations are at a frequency which is a function of an impedance of the NFC antenna;

determining that the number of occurrences of the frequency oscillations is greater than a frequency deviation threshold from a reference frequency;

waking up an NFC chip including a crystal oscillator coupled to the NFC antenna and matching network in response to the determination; and

performing a NFC polling procedure using the NFC chip and the crystal oscillator to determine whether the frequency deviation is based on the presence of a remote NFC device in response to the determination.

20. The non-transitory computer-readable medium of claim 19, further comprising code for:

calibrating the LPO using the crystal oscillator, wherein the crystal oscillator provides a comparatively higher quality reference clock value to a reference clock value associated with the LPO.

21. The non-transitory computer-readable medium of claim 20, wherein the calibration is performed periodically.

22. The non-transitory computer-readable medium of claim 20, wherein the calibration is performed when a subsystem that uses the crystal oscillator is activated.

23. The non-transitory computer-readable medium of claim 20, wherein the calibration is performed once per an integer number of wake-up cycles, wherein the integer is greater than one.

24. The non-transitory computer-readable medium of claim 19, wherein the monitoring is performed continuously.

25. The non-transitory computer-readable medium of claim 19, wherein the number of occurrences is averaged over a time duration.

26. The non-transitory computer-readable medium of claim 19, wherein the reference frequency is adaptively determined based on one or more previously determined values.

27. The non-transitory computer-readable medium of claim 19, wherein the number of occurrences of the frequency oscillations is based on changes in impedance associated with the NFC antenna.

28. An apparatus for wireless communications, comprising:

a near field communication (NFC) antenna and matching network;

a calibrated low power oscillator (LPO) circuit connected to the NFC antenna and the matching network and configured to monitor frequency oscillations associated with the NFC antenna;

an NFC chip;

a crystal oscillator; and

a processing system coupled to at least one of the LPO circuit or the NFC antenna and matching network and configured to;

generate the frequency oscillations using the LPO connected to the NFC antenna;

count a number of occurrences of the frequency oscillations using a frequency counter connected to the LPO, wherein the frequency oscillations are at a frequency which is a function of an impedance of the NFC antenna;

determine that a number of occurrences of the frequency oscillations is greater than a frequency deviation threshold from a reference frequency;

wake up the NFC chip and the crystal oscillator coupled to the NFC antenna and matching network in response to the determination; and

perform a NFC polling procedure using the NFC chip and the crystal oscillator to determine whether the frequency deviation is based on the presence of a remote NFC device in response to the determination.

29. The apparatus of claim 28, wherein the crystal oscillator is configured to calibrate the LPO, wherein the crystal oscillator provides a comparatively higher quality reference clock value to a reference clock value associated with the LPO.

30. The apparatus of claim 28, wherein the calibration is performed periodically.

31. The apparatus of claim 29, wherein the calibration is performed when a subsystem that uses the crystal oscillator is activated.

32. The apparatus of claim 29, wherein the calibration is performed once per an integer number of wake-up cycles, wherein the integer is greater than one.

33. The apparatus of claim 28, wherein the processing system monitors continuously.

34. The apparatus of claim 28, wherein the number of occurrences is averaged over a time duration.

35. The apparatus of claim 28, wherein the reference frequency is adaptively determined based on one or more previously determined values.

36. The apparatus of claim 28, wherein the number of occurrences of the frequency oscillations is based on changes in impedance associated with the NFC antenna.