ADAPTIVE SIGNAL SCALING IN NFC TRANSCEIVERS

• US 20130109304A1
• Filed: 10/26/2011
• Published: 05/02/2013
• Est. Priority Date: 10/26/2011
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Savoj, Jafar, Marcu, Cristian
• Granted Patent: US 9,384,373 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

Abstract

Exemplary embodiments are directed to adaptive signal scaling in NFC transceivers. A transceiver may include a programmable load modulation element configured for load modulation in a tag mode. Further, the transceiver may include a sensing element for measuring an amount of power harvested by the transceiver in the tag mode. The transceiver may also include a controller configured for adjusting a depth of load modulation of the programmable load modulation element depending on the amount of power harvested.

Claims

1. A transceiver, comprising:

a programmable load modulation element configured for load modulation in a tag mode;

a sensing element for measuring an amount of power harvested by the transceiver in the tag mode; and

a controller coupled to each of the programmable load modulation element and the sensing element and configured for adjusting a depth of load modulation of the programmable load modulation element depending on the amount of power harvested.

2. The transceiver of claim 1, the programmable load modulation element comprising a current digital-to-analog converter (DAC).

3. The transceiver of claim 1, the sensing element comprising a rectifier.

4. The transceiver of claim 1, the controller further configured for comparing the measured amount of power harvested to a minimum harvested power threshold.

5. The transceiver of claim 4, the controller further configured to increase the depth of load modulation if the measured amount of power harvested is greater than the minimum harvested power threshold.

6. The transceiver of claim 4, the controller further configured to decrease the depth of load modulation if the measured amount of power harvested is less than the minimum harvested power threshold.

7. A transceiver, comprising:

an attenuator for attenuating an input signal;

a sensing element coupled to the attenuator and configured for measuring an amplitude of the input signal; and

a controller configured for adjusting an attenuation ratio of the attenuator depending on the amplitude of the input signal.

8. The transceiver of claim 7, the attenuator comprising one of a resistive network and a capacitive network.

9. The transceiver of claim 7, the attenuator comprising a resistive network configured to include one or more resistive paths.

10. The transceiver of claim 7, the attenuator comprising a capacitive network configured to include one or more capacitive paths.

11. The transceiver of claim 7, the sensing element comprising an envelope detector.

12. The transceiver of claim 7, the controller further configured for comparing the measured amplitude of the input signal to a maximum threshold amplitude.

13. The transceiver of claim 12, the controller further configured to increase the attenuation ratio if the measured amplitude of the input signal is greater than the maximum threshold amplitude.

14. The transceiver of claim 12, the controller further configured to decrease the attenuation ratio if the measured amplitude of the input signal is less than the maximum threshold amplitude.

15. A method, comprising:

measuring an amplitude of a received input signal;

comparing the amplitude of the received input signal to a maximum threshold amplitude; and

adjusting an attenuation ratio of an attenuator in response to comparing the amplitude of the received input signal to the maximum threshold amplitude.

16. The method of claim 15, the measuring comprising measuring the amplitude with an envelope detector.

17. The method of claim 15, the adjusting comprising adjusting an attenuation ratio of a voltage divider configured to receive the input signal.

18. A method, comprising:

measuring an amount of power harvested by a transceiver during load modulation;

comparing the amount of power harvested to a minimum harvested power threshold; and

adjusting a depth of load modulation in response to comparing the amount of power harvested to the minimum harvested power threshold.

19. The method of claim 18, the measuring an amount of power harvested comprising measuring an amount of power at an output of a rectifier.

20. The method of claim 18, the adjusting comprising adjusting the depth of load modulation with one or more drivers of a current DAC.

21. A device, comprising:

means for measuring an amplitude of a received input signal; and

means for comparing the amplitude of the received input signal to a maximum threshold amplitude; and

means for adjusting an attenuation ratio of an attenuator in response to comparing the amplitude of the received input signal to the maximum threshold amplitude.

22. A device, comprising:

means for measuring an amount of power harvested by a transceiver during load modulation;

means for comparing the amount of power harvested to a minimum harvested power threshold; and

means for adjusting a depth of load modulation in response to comparing the amount of power harvested to the minimum harvested power threshold.

23. A transceiver, comprising:

an adaptive scaling element;

a sensing element coupled to the adaptive scaling element and configured to sense at least one parameter of the transceiver; and

a controller coupled to each of the scaling element and the sensing element and configured to adaptively scale one of a received input signal and a load modulation depth with the adaptive scaling element depending on the at least one sensed parameter.

24. The transceiver of claim 23, the adaptive scaling element comprising an attenuator and the sensing element comprising an envelope detector.

25. The transceiver of claim 23, the adaptive scaling element comprising a programmable load modulation element and the sensing element comprising a rectifier.