NEAR FIELD COMMUNICATIONS APPARATUS

• US 20130017782A1
• Filed: 07/11/2012
• Published: 01/17/2013
• Est. Priority Date: 07/11/2011
• Status: Active Grant

• Current Assignee: Qualcomm technologies international, ltd. (Qualcomm, Inc.)
• Original Assignee: Cambridge Silicon Radio Limited (Qualcomm, Inc.)
• Inventors: Tay, Zern, Patel, Shyam, McFarthing, Anthony
• Granted Patent: US 9,698,871 B2
• Time in Patent Office: Days
• US Class Current: 455/41.1
• CPC Class Codes: G06K 7/10237 the reader and the record carrier being capable of selectively switching between reader and record carrier appearance, e.g. in near field communication [NFC] devices where the NFC device may function as an RFID reader or as an RFID tag
• CPC Class Codes: H04B 5/22 Capacitive coupling
• CPC Class Codes: H04B 5/70 specially adapted for specific purposes

Abstract

A near field communications apparatus comprising a signal source, a transmit antenna and means for detecting a change in the input impedance of the transmit antenna to detect the presence of a device which is compatible with the apparatus.

Claims

1. A near field communications apparatus comprising a signal source, a transmit antenna and means for detecting a change in the input impedance of the transmit antenna to detect the presence of a device which is compatible with the apparatus.

2. A near field communications apparatus according to claim 1 wherein the signal source is configured to generate a signal at a constant frequency.

3. A near field communications apparatus according to claim 1 wherein the signal source is configured to generate a chirp signal.

4. A near field communications apparatus according to claim 1 wherein the means for detecting a change in the input impedance of the transmit antenna comprises a quadrature receiver.

5. A near field communications apparatus according to claim 1 wherein the means for detecting a change in the input impedance of the transmit antenna comprises a scalar receiver and a level detector.

6. A near field communications apparatus according to claim 1 wherein the means for detecting a change in the input impedance of the transmit antenna is configured to detect a change in the real part of the input impedance of the antenna.

7. A near field communications apparatus according to claim 1 wherein the means for detecting a change in the input impedance of the transmit antenna is configured to detect a change in the imaginary part of the input impedance of the antenna.

8. A near field communications apparatus according to claim 3 wherein the means for detecting a change in the input impedance of the transmit antenna is configured to detect a change in the input impedance at a frequency associated with a resonant frequency of a transmit section of the apparatus.

9. A near field communications apparatus according to claim 3 wherein the signal source is configured to generate a first chirp signal in a first frequency range and a second chirp signal in a second frequency range.

19. A near field communications apparatus according to claim 2 wherein the means for detecting a change in the input impedance of the transmit antenna comprises a scalar receiver and a level detector.

20. A near field communications apparatus according to claim 3 wherein the means for detecting a change in the input impedance of the transmit antenna comprises a scalar receiver and a level detector.

10. A method of detecting a near field communications device, the method comprising transmitting a signal generated by signal source using a transmit antenna and detecting a change in the input impedance of the transmit antenna.

11. A method according to claim 10 wherein the signal generated by the signal source is at a constant frequency.

12. A method according to claim 10 wherein the signal is a chirp signal.

13. A method according to claim 10 wherein a change in the input impedance of the transmit antenna is detected using a quadrature receiver.

14. A method according to claim 10 where a change in the input impedance of the transmit antenna is detected using a scalar receiver and a level detector.

15. A method according to claim 10 wherein detecting a change in the input impedance of the transmit antenna comprises detecting a change in the real part of the input impedance of the antenna.

16. A method according to claim 10 wherein detecting a change in the input impedance of the transmit antenna comprises detecting a change in the imaginary part of the input impedance of the antenna.

17. A method according to claim 12 wherein detecting a change in the input impedance of the transmit antenna comprises detecting a change in the input impedance at a frequency associated with a resonant frequency of a transmit section associated with the antenna.

18. A method according to claim 12 wherein a first chirp signal in a first frequency range and a second chirp signal in a second frequency range are generated.