DIRECT POWER TRANSMISSION LOAD MODULATION IN NEAR FIELD COMMUNICATION DEVICES

• US 20140273830A1
• Filed: 06/03/2013
• Published: 09/18/2014
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wong, Angelica, Sabouri, Faramarz
• Granted Patent: US 9,450,646 B2
• Time in Patent Office: Days
• US Class Current: 455/41.1
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• 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: H04B 5/72 for local intradevice communication

Abstract

An NFC initiator device requests a passive communication mode by modulating a request onto a first carrier signal. In response thereto, the target device transmits a second carrier signal while still receiving the first carrier signal from the initiator device. The target device may modulate data onto the second carrier signal to convey information to the initiator device. The initiator device may detect changes in the load provided by the target device to interpret the data conveyed by the target device.

Claims

1. A method of operating a near-field communication (NFC) device as a target device during an NFC session, the method comprising:

receiving a polling command from an initiator device requesting a passive communication mode;

receiving a first carrier signal from the initiator device during the NFC session;

transmitting a second carrier signal from the target device while the first carrier signal is being received; and

modulating data onto the second carrier signal.

2. The method of claim 1, wherein after the target device receives the polling command, the first carrier signal remains un-modulated.

3. The method of claim 1, wherein the target device continuously receives the first carrier signal and continuously transmits the second carrier signal during the NFC session.

4. The method of claim 1, wherein the first carrier signal and the second carrier signal super-position to form a composite waveform indicative of the modulated data.

5. The method of claim 4, wherein an amplitude of the composite waveform indicates a phase relationship between the first carrier signal and the second carrier signal.

6. The method of claim 5, wherein the target device is to modulate the data by adjusting the phase relationship between the first carrier signal and the second carrier signal.

7. The method of claim 1, wherein the transmitting comprises:

extracting clock information from the received first carrier signal; and

generating the second carrier signal using the extracted clock information.

8. The method of claim 1, wherein the modulating comprises:

adjusting a phase of the second carrier signal to encode the data onto the second carrier signal.

9. The method of claim 1, wherein the modulating comprises:

adjusting an amplitude of the second carrier signal to encode the data onto the second carrier signal.

10. The method of claim 1, wherein the modulating comprises:

intermittingly terminating the second carrier signal while still receiving the first carrier signal.

11. A computer-readable medium containing program instructions that, when executed by a processor of a target device during a near-field communication (NFC) session, cause the target device to:

receive a polling command from an initiator device requesting a passive communication mode;

receive a first carrier signal from the initiator device during the NFC session;

transmit a second carrier signal from the target device while the first carrier signal is being received; and

modulate data onto the second carrier signal.

12. The computer-readable medium of claim 11, wherein after the target device receives the polling command, the first carrier signal remains un-modulated.

13. The computer-readable medium of claim 11, wherein execution of the program instructions further causes the target device to:

continuously receive the first carrier signal during the NFC session; and

continuously transmit the second carrier signal during the NFC session.

14. The computer-readable medium of claim 11, wherein the first carrier signal and the second carrier signal super-position to form a composite waveform indicative of the modulated data.

15. The computer-readable medium of claim 14, wherein an amplitude of the composite waveform indicates a phase relationship between the first carrier signal and the second carrier signal.

16. The computer-readable medium of claim 15, wherein the target device is to modulate the data by adjusting the phase relationship between the first carrier signal and the second carrier signal.

17. The computer-readable medium of claim 11, wherein execution of the program instructions to transmit the second carrier signal causes the target device to:

extract clock information from the received first carrier signal; and

generate the second carrier signal using the extracted clock information.

18. The computer-readable medium of claim 11, wherein execution of the program instructions to modulate the second carrier signal causes the target device to:

adjust a phase of the second carrier signal to encode the data onto the second carrier signal.

19. The computer-readable medium of claim 11, wherein execution of the program instructions to modulate the second carrier signal causes the target device to:

adjust an amplitude of the second carrier signal to encode the data onto the second carrier signal.

20. The computer-readable medium of claim 11, wherein execution of the program instructions to modulate the second carrier signal causes the target device to:

intermittingly terminate the second carrier signal while still receiving the first carrier signal.

21. A near-field communication (NFC) device configured to operate as a target device during a passive communication mode, comprising:

an antenna to receive a first carrier signal from an initiator device, wherein the first carrier signal includes a request for the passive communication mode; and

a transmitter, coupled to the NFC antenna, to transmit a second carrier signal containing data to the initiator device in response to the request for the passive communication mode.

22. The NFC device of claim 21, further comprising:

a phase-locked loop (PLL) circuit, coupled to the antenna and to the transmitter, to extract clock information from the received first carrier signal.

23. The NFC device of claim 22, wherein the transmitter is to generate the second carrier signal using the extracted clock information.

24. The NFC device of claim 21, wherein the transmitter is to continuously transmit the second carrier signal while the first carrier signal is continuously received by the NFC antenna.

25. The NFC device of claim 21, wherein the first carrier signal and the second carrier signal super-position to form a composite waveform indicative of the data.

26. The NFC device of claim 25, wherein an amplitude of the composite waveform indicates a phase relationship between the first carrier signal and the second carrier signal.

27. The NFC device of claim 26, wherein the target device is to modulate the data by adjusting the phase relationship between the first carrier signal and the second carrier signal.

28. The NFC device of claim 21, wherein the transmitter is to modulate the data onto the second carrier signal by adjusting a delay value of a pulse-width modulated (PWM) signal.

29. The NFC device of claim 28, wherein the transmitter comprises:

a carrier phase control circuit including a look-up table to store a plurality of phase values to be used when adjusting the delay value of the PWM signal.

30. The NFC device of claim 29, further comprising:

a phase-locked loop (PLL) circuit, coupled to the antenna and to the transmitter, to extract clock information from the received first carrier signal, wherein the PLL circuit is to generate an output clock signal in response to the extracted clock information, and the look-up table is to select one of the plurality of phase values in response to the output clock signal.

31. A near-field communication (NFC) device configured to operate as a target device during an NFC session, the NFC device comprising:

means for receiving a polling command from an initiator device requesting a passive communication mode;

means for receiving a first carrier signal from the initiator device during the NFC session;

means for transmitting a second carrier signal from the target device while the first carrier signal is being received; and

means for modulating data onto the second carrier signal.

32. The NFC device of claim 31, wherein the target device is to continuously receive the first carrier signal and is to continuously transmit the second carrier signal during the NFC session.

33. The NFC device of claim 31, wherein the first carrier signal and the second carrier signal super-position to form a composite waveform indicative of the modulated data.

34. The NFC device of claim 33, wherein an amplitude of the composite waveform indicates a phase relationship between the first carrier signal and the second carrier signal.

35. The NFC device of claim 34, wherein the target device is to modulate the data by adjusting the phase relationship between the first carrier signal and the second carrier signal.

36. The NFC device of claim 31, wherein the means for transmitting is to:

extract clock information from the received first carrier signal; and

generate the second carrier signal using the extracted clock information.

37. The NFC device of claim 31, wherein the means for modulating is to adjust a phase of the second carrier signal to encode the data onto the second carrier signal.

38. The NFC device of claim 31, wherein the means for modulating is to adjust an amplitude of the second carrier signal to encode the data onto the second carrier signal.

39. The NFC device of claim 31, wherein the means for modulating is to intermittingly terminate the second carrier signal while still receiving the first carrier signal.