NFC OR RFID DEVICE RF DETUNING DETECTION AND DRIVER OUTPUT POWER REGULATION

• US 20170104468A1
• Filed: 10/12/2015
• Published: 04/13/2017
• Est. Priority Date: 10/12/2015
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Kormann, Leonhard, Wobak, Markus, Nunziata, Fred George
• Granted Patent: US 10,164,600 B2
• Time in Patent Office: Days
• CPC Class Codes: G06K 7/10148 the step consisting of dynamically tuning the resonant circuit of the interrogation device that is emitting the interrogation signal, e.g. for impedance matching inside of the interrogation device for tuning related to loop aerials in general H01Q7/00
• CPC Class Codes: G06K 7/10158 methods and means used by the interrogation device for reliably powering the wireless record carriers using an electromagnetic interrogation field
• CPC Class Codes: G06K 7/10217 parameter settings controlling the transmission power of the interrogator
• CPC Class Codes: H03H 7/38 Impedance-matching networks
• CPC Class Codes: H04B 5/77 for interrogation

Abstract

A near field communication (NFC) or Radio Frequency Identification (RFID) reader device for contact-less communication includes a transmitter block connected to an antenna via a matching circuitry. An electromagnetic carrier signal and modulated data information are emitted via this main antenna. Any secondary object brought into the vicinity of the main antenna influences the primary resonant circuit resulting in a load change seen by the transmitter. This detuning can cause increased power consumption, RF (Radio Frequency) standard incompliance, and device damage. The present disclosure describes devices and methods on how to detect detuning and how to regulate the transmitter'"'"'s output.

Claims

1. A method for detuning detection and transmitter (TX) current regulation, the method comprising:

monitoring, by a sensor within a transmitter, a transmitter (TX) current and/or voltage;

detecting a detuning of an antenna and matching network by a change in the TX current and/or voltage;

in response to detection of the detuning, regulating the TX current.

2. The method of claim 1, wherein regulation of the TX current is achieved by changing a transmitter supply voltage or a transmitter internal resistance.

3. The method of claim 2, wherein changing the transmitter supply voltage or the transmitter internal resistance is controlled using a control unit.

4. The method of claim 3, wherein changing the transmitter supply voltage or the transmitter internal resistance is performed by an active attenuator.

5. The method of claim 1, wherein the TX current is regulated by using a plurality of gears, wherein each one of the plurality of gears represents a discrete power configuration for the transmitter, and further wherein the transmitter starts in a first gear that corresponds to a configuration of highest transmission power, and further wherein all higher sears correspond to configurations having reduced transmission power.

6. The method of claim 1, wherein the transmitter is a Near Field Communication (NFC) transmitter or a Radio Frequency Identification (RFID) transmitter.

7. A method for detuning detection and transmitter (TX) current regulation, the method comprising:

monitoring a voltage or current of an antenna and matching network;

detecting a detuning of the antenna and matching network by a change in the voltage or current of the antenna and matching network;

in response to detection of the detuning, regulating a transmitter (TX) current.

8. The method of claim 7, wherein regulation of the TX current is achieved by changing a transmitter supply voltage or a transmitter internal resistance.

9. The method of claim 8, wherein changing the transmitter supply voltage or the transmitter internal resistance is controlled using a control unit.

10. The method of claim 9, wherein changing the transmitter supply voltage or the transmitter internal resistance is performed by an active attenuator.

11. The method of claim 7, wherein monitoring the voltage or current of the antenna and matching network comprises:

monitoring the voltage or current at one or more nodes of the antenna and matching network.

12. The method of claim 7, wherein the TX current is regulated by using a plurality of gears, wherein each one of the plurality of gears represents a discrete power configuration for a transmitter, and further wherein the transmitter starts in a first gear that corresponds to a configuration of highest transmission power, and further wherein all higher sears correspond to configurations having reduced transmission power.

13. The method of claim 7 further comprising:

monitoring, by a sensor within a transmitter, a transmitter (TX) current and/or voltage;

detecting a detuning of the antenna and matching network by a change in the TX current and/or voltage and/or a change in the voltage or current of the antenna and matching network.

14. The method of claim 7, wherein the transmitter is a Near Field Communication (NFC) transmitter or a Radio Frequency Identification (RFID) transmitter.

15. A device for detuning detection and transmitter (TX) current regulation, the device comprising:

an active attenuator configured to generate a transmitter (TX) voltage;

an antenna and matching circuit configured to be driven by a TX current corresponding to the TX voltage;

a first sensor configured to monitor the TX current and/or voltage;

a second sensor configured to monitor a voltage or current of the antenna and matching network;

a control unit configured to;

detecting a detuning of the antenna and matching network based on a change in the TX current and/or voltage and/or a change in the voltage or current of the antenna and matching network,

and, in response to detection of the detuning, regulating the TX current.

16. The device of claim 15, wherein the control unit regulates the TX current by changing a TX supply voltage or a TX internal resistance.

17. The device of claim 16 further comprising:

a pre-driver configured to generate an amplified signal for input to the active attenuator.

18. The device of claim 17, wherein the second sensor monitors the voltage or current of the antenna and matching network at one or more nodes of the antenna and matching network.

19. The device of claim 17, wherein the TX current is regulated by using a plurality of gears, wherein each one of the plurality of gears represents a discrete power configuration for a transmitter, and further wherein the transmitter starts in a first gear that corresponds to a configuration of highest transmission power, and further wherein all higher gears correspond to configurations having reduced transmission power.

20. The device of claim 15, wherein the device is a Near Field Communication (NFC) device or a Radio Frequency Identification (RFID) device.