CONTACTLESS DATA RECEPTION

• US 20100243737A1
• Filed: 03/31/2009
• Published: 09/30/2010
• Est. Priority Date: 03/31/2009
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Kargl, Walter, Ehrlich, Edmund, Emsenhuber, Matthias
• Granted Patent: US 8,905,310 B2
• Time in Patent Office: Days
• US Class Current: 235/439
• 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 7/10178 including auxiliary means for focusing, repeating or boosting the electromagnetic interrogation field comparable booster antennas integrated on the record carrier itself G06K19/07794
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles
• CPC Class Codes: H04B 5/26 using coils

Abstract

A contactless device including a transmission antenna configured to transmit a transmission signal; a pickup antenna configured to detect a field generated by a pickup signal, which comprises a response signal transmitted from another contactless device and the transmission signal; and a cancellation circuit configured to subtract a voltage of the transmission antenna from a voltage of the pickup antenna.

Claims

1. A contactless device, comprising:

a transmission antenna configured to transmit a transmission signal;

a pickup antenna configured to detect a field generated by a pickup signal, which comprises a response signal transmitted from another contactless device and the transmission signal; and

a cancellation circuit configured to subtract a voltage of the transmission antenna from a voltage of the pickup antenna.

2. The contactless device of claim 1, wherein the cancellation circuit comprises:

a current measuring device configured to measure a current corresponding to the voltage of the transmission antenna; and

a subtraction device configured to perform the subtraction.

3. The contactless device of claim 2, wherein the cancellation circuit further comprises:

a first amplifier coupled between the current measuring device and the subtraction device, and configured to amplify the voltage of the transmission antenna; and

a second amplifier coupled between the pickup antenna and the subtraction device, and configured to amplify the voltage of the pickup antenna.

4. The contactless device of claim 2, wherein the current measuring device is a resistor.

5. The contactless device of claim 2, wherein the current measuring device is a capacitor.

6. The contactless device of claim 2, wherein the current measuring device is an inductor.

7. The contactless device of claim 2, wherein the subtraction device is a differential amplifier.

8. The contactless device of claim 1, wherein the pickup antenna is located in the plane of the transmission antenna.

9. The contactless device of claim 1, wherein the pickup antenna is centered with respect to the transmission antenna.

10. The contactless device of claim 1, wherein the cancellation circuit comprises:

a voltage measuring device configured to measure the voltage across the transmission antenna; and

a subtraction device configured to perform the subtraction.

11. The contactless device of claim 10, wherein the voltage measuring device is a capacitive divider.

12. The contactless device of claim 10, wherein the voltage measuring device is a resistive divider.

13. The contactless device of claim 1, further comprising a second pickup antenna configured to detect the transmission signal only.

14. The contactless device of claim 1, wherein the cancellation circuit is configured to perform the subtraction in an analog manner.

15. The contactless device of claim 1, wherein the cancellation circuit comprises:

a first analog-to-digital converter configured to convert the voltage of the transmission antenna from analog to digital form; and

a second analog-to-digital converter configured to convert the voltage of the pickup antenna from analog to digital form,

wherein the cancellation circuit is configured to perform the subtraction in a digital manner.

16. The contactless device of claim 15, wherein the cancellation circuit performs the subtraction continuously.

17. The contactless device of claim 15, wherein the cancellation circuit performs the subtraction using a static voltage of the transmission antenna.

18. The contactless device of claim 1, wherein the contactless device is one of a contactless reader and a contactless card.

19. A contactless communication system comprising:

a first contactless device; and

a second contactless device, comprising;

a transmission antenna configured to transmit a transmission signal;

a pickup antenna configured to detect a field generated by a pickup signal, which comprises a response signal transmitted from the first contactless device, and the transmission signal; and

a cancellation circuit configured to subtract a voltage of the transmission antenna from a voltage of the pickup antenna.

20. The contactless communication system of claim 19, wherein the first contactless device comprises:

a further transmission antenna configured to transmit a further transmission signal;

a further pickup antenna configured to detect a field generated by a further pickup signal, which comprises a response signal transmitted from the second contactless device, and the further transmission signal; and

a further cancellation circuit configured to subtract a voltage of the further transmission antenna from a voltage of the further pickup antenna.

21. A method for detecting a response signal at a contactless device, comprising:

transmitting a transmission signal by transmission antenna;

detecting a field generated by a pickup signal, which comprises the response signal transmitted from another contactless device and the transmission signal, by a pickup antenna; and

subtracting a voltage of the transmission antenna from a voltage of the pickup antenna.

22. The method of claim 21, further comprising measuring the voltage of the transmission antenna continuously.

23. The method of claim 21, further comprising:

measuring the voltage of the transmission antenna; and

storing the voltage of the transmission antenna,

wherein the subtracting step comprises subtracting the stored voltage of the transmission antenna from the voltage of the pickup antenna.

24. The method of claim 21, further comprising:

converting the voltage of the transmission antenna from analog to digital form; and

converting the voltage of the pickup antenna from analog to digital form;

wherein the subtraction is performed in a digital manner.

25. A contactless device, comprising:

a transmission antenna configured to transmit a transmission signal;

a pickup antenna configured to detect a field generated by a pickup signal, which comprises a response signal transmitted from another contactless device and the transmission signal; and

a cancellation means for subtracting a voltage of the transmission antenna from a voltage of the pickup antenna.