METHODS AND APPARATUS FOR IMPROVING REMOTE NFC DEVICE DETECTION USING A LOW POWER OSCILLATOR CIRCUIT

• US 20140370803A1
• Filed: 06/18/2013
• Published: 12/18/2014
• Est. Priority Date: 06/18/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Haverinen, Anssi Kaleva, Wong, Angelica, Brockenbrough, Roger, Lee, Sang-Min, Reynolds, Todd
• Granted Patent: US 9,698,872 B2
• Time in Patent Office: Days
• US Class Current: 455/41.1
• 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 inductive communications, comprising:

monitoring frequency oscillations associated with a near field communication (NFC) antenna using a calibrated low power oscillator (LPO);

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

performing a NFC polling procedure in response to the determination.

2. The method of claim 1, further comprising:

calibrating the LPO using a 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 monitoring further comprising:

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

counting the number of occurrences using a frequency counter connected to the LPO.

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

10. The method of claim 1, wherein the frequency oscillations from the reference frequency are based on changes in impedance associated with the NFC antenna.

11. An apparatus for inductive communications, comprising:

means for monitoring frequency oscillations associated with a near field communication (NFC) antenna using a calibrated low power oscillator (LPO);

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

means for performing a NFC polling procedure in response to the determination.

12. The apparatus of claim 11, further comprising:

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

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

14. The apparatus of claim 12, wherein the calibration is performed when a subsystem that uses the crystal oscillator is activated.

15. The apparatus of claim 12, wherein the calibration is performed once per an integer number of wake-up cycles, wherein the integer is greater than one.

16. The apparatus of claim 11, wherein the monitoring is performed continuously.

17. The apparatus of claim 11, wherein the number of occurrences is averaged over a time duration.

18. The apparatus of claim 11, wherein the means for monitoring are further configured to:

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

count the number of occurrences using a frequency counter connected to the LPO.

19. The apparatus of claim 11, wherein the reference frequency is adaptively determined based on one or more previously determined values.

20. The apparatus of claim 11, wherein the frequency oscillations from the reference frequency are based on changes in impedance associated with the NFC antenna.

21. A computer program product, comprising:

a computer-readable medium comprising code for;

monitoring frequency oscillations associated with a near field communication (NFC) antenna using a calibrated low power oscillator (LPO);

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

performing a NFC polling procedure in response to the determination.

22. The computer program product of claim 21, further comprising code for:

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

23. The computer program product of claim 22, wherein the calibration is performed periodically.

24. The computer program product of claim 22, wherein the calibration is performed when a subsystem that uses the crystal oscillator is activated.

25. The computer program product of claim 22, wherein the calibration is performed once per an integer number of wake-up cycles, wherein the integer is greater than one.

26. The computer program product of claim 21, wherein the monitoring is performed continuously.

27. The computer program product of claim 21, wherein the number of occurrences is averaged over a time duration.

28. The computer program product of claim 21, further comprising code for:

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

counting the number of occurrences using a frequency counter connected to the LPO.

29. The computer program product of claim 21, wherein the reference frequency is adaptively determined based on one or more previously determined values.

30. The computer program product of claim 21, wherein the frequency oscillations from the reference frequency are based on changes in impedance associated with the NFC antenna.

31. An apparatus for inductive communications, comprising:

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

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

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

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.

32. The apparatus of claim 31, wherein the apparatus further comprises a crystal oscillator, and 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.

33. The apparatus of claim 31, wherein the calibration is performed periodically.

34. The apparatus of claim 32, wherein the calibration is performed when a subsystem that uses the crystal oscillator is activated.

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

36. The apparatus of claim 31, wherein the processing system monitors continuously.

37. The apparatus of claim 31, wherein the number of occurrences is averaged over a time duration.

38. The apparatus of claim 31, wherein the processing system is further configured to:

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

count the number of occurrences using a frequency counter connected to the LPO.

39. The apparatus of claim 31, wherein the reference frequency is adaptively determined based on one or more previously determined values.

40. The apparatus of claim 31, wherein the frequency oscillations from the reference frequency are based on changes in impedance associated with the NFC antenna.