ADAPTIVE NFC TRANSCEIVERS

• US 20130109305A1
• 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, Wong, Angelica
• Granted Patent: US 9,292,782 B2
• Time in Patent Office: Days
• US Class Current: 455/41.1
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• 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 a transceiver having an adaptive matching circuit. A transceiver may include a matching circuit that is coupled to an antenna and includes an adjustable capacitor. The transceiver may further include an envelope detector coupled to the antenna and a sensor for sensing a voltage at an output of the envelope detector.

Claims

1. A transceiver, comprising:

a matching circuit coupled to an antenna and including an adjustable capacitor;

an envelope detector coupled to the antenna; and

a sensor for sensing a voltage at an output of the envelope detector.

2. The transceiver of claim 1, the envelope detector coupled to the antenna through a resistive network.

3. The transceiver of claim 1, the resistive network comprising a first resistor external to an associated chip and a second resistor integrated on the associated chip.

4. The transceiver of claim 1, further comprising a control module for adjusting a capacitance of the adjustable capacitor.

5. The transceiver of claim 4, the control module for adjusting a capacitance of the adjustable capacitor in response to a change in an inductance at the antenna.

6. The transceiver of claim 1, further comprising an antenna driver coupled in parallel with the adjustable capacitor.

7. The transceiver of claim 1, the matching circuit comprising a voltage divider including the adjustable capacitor and an other capacitor.

8. The transceiver of claim 7, the adjustable capacitor integrated on an associated chip and the other capacitor external to the associated chip.

9. A method, comprising:

measuring a transmitter output voltage while a capacitor of a matching network is at a first capacitance value;

measuring the transmitter output voltage while the capacitor is of at least one other capacitance value; and

setting the capacitor to a capacitance value associated with a maximum measured transmitter output voltage.

10. The method of claim 9, further comprising increasing the capacitance value of the capacitor after measuring the transmitter output voltage while the capacitor is at the first capacitance value.

11. The method of claim 10, the increasing comprising increasing the capacitance value of the capacitor with a control module.

12. The method of claim 9, further comprising comparing the transmitter output voltage associated with the first capacitance value to the transmitter output voltage associated with a second capacitance value.

13. The method of claim 9, the measuring a transmitter output voltage while a capacitor of a matching network is at a first capacitance value comprising measuring a voltage at an output of an envelope detector.

14. The method of claim 9, the measuring a transmitter output voltage while the capacitor of a matching network is at at least one other capacitance value comprising measuring a voltage at an output of an envelope detector.

15. The method of claim 9, further comprising increasing the capacitance value if the transmitter output voltage associated with a second capacitance value is greater than the transmitter output voltage associated with the first capacitance value.

16. A transceiver, comprising:

an antenna;

a variable capacitor coupled in parallel with the antenna; and

a control module for varying a capacitance of the variable capacitor to modify an amount of power delivered to the antenna.

17. The transceiver of claim 16, further comprising:

an envelope detector; and

a sensor for sensing a voltage at an output of the envelope detector.

18. The transceiver of claim 17, the control module configured for sensing a change in the voltage at the output of the envelope detector.

19. A method, comprising:

varying a capacitance of a variable capacitor coupled in parallel with an antenna; and

detecting a maximum amount of power delivered to the antenna in response to varying the capacitance of the variable capacitor.

20. The method of claim 19, further comprising comparing a current voltage an output of an envelope detector to a previous voltage at the output of the envelope detector to detect the maximum amount of power.

21. The method of claim 19, the varying comprising setting the capacitor to a capacitance value associated with a previous voltage if a current voltage is less than a previous voltage.

22. The method of claim 19, further comprising detecting a maximum voltage at an output of an envelope detector in response to varying the capacitance of the variable capacitor.

23. The method of claim 19, the varying comprising increasing the capacitor value if a previous voltage at an output of an envelope detector less than a current voltage at the output of an envelope detector.

24. A device, comprising:

means for measuring a transmitter output voltage while a capacitor of a matching network is at a first capacitance value; and

means for measuring the transmitter output voltage while the capacitor is at at least one other capacitance value; and

means for setting the capacitor to a capacitance value associated with a maximum measured transmitter output voltage.

25. A device, comprising:

means for varying a capacitance of a variable capacitor coupled in parallel with an antenna; and

means for detecting a maximum amount of power delivered to the antenna in response to varying the capacitance of the variable capacitor.