RFID tags combining signals received from multiple RF ports

• US 20070216533A1
• Filed: 05/15/2007
• Published: 09/20/2007
• Est. Priority Date: 03/31/2004
• Status: Active Grant

• Current Assignee: Impinj, Inc.
• Original Assignee: Impinj, Inc.
• Inventors: Onen, Omer, Hyde, John, Oliver, Ronald
• Granted Patent: US 7,525,438 B2
• Time in Patent Office: Days
• US Class Current: 340/572.400
• 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 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 19/07767 the first and second communication means being two different antennas types, e.g. dipole and coil type, or two antennas of the same kind but operating at different frequencies

Abstract

Circuits, devices and methods for use in RFID tags include receiving multiple RF signals from multiple ports. The signals are added after some processing, to produce a single combined signal. Additional components process the single combined signal by itself.

Claims

1. A circuit for use in an RFID tag, comprising:

a first RF port configured to receive a first signal (first received signal);

a second RF port configured to receive a second signal (second received signal);

a signal combiner for generating a combined signal from the first received signal and the second received signal, the signal combiner including a first envelope detector configured to generate a first processed signal from the first received signal, a second envelope detector configured to generate a second processed signal from the second received signal, and an adder configured to generate the combined signal from the first processed signal and the second processed signal; and

an analog to digital converter for generating a digital signal from the combined signal.

2. The circuit of claim 1, wherein

the adder is configured to add together the first processed signal and the second processed signal.

3. The circuit of claim 1, wherein

the first envelope detector includes an AC diode.

4. The circuit of claim 1, wherein

the adder includes a node.

5. The circuit of claim 4, further comprising:

a capacitor coupled to the node.

6. The circuit of claim 5, further comprising:

a discharging component for discharging the capacitor.

7. The circuit of claim 6, wherein

the discharging component includes at least one of a resistor, a current source, and a transistor.

8. The circuit of claim 1, wherein

the analog to digital converter includes a peak detector to detect peaks of the combined signal.

9. The circuit of claim 1, wherein

the analog to digital converter includes a comparator.

10. A device for use in an RFID tag comprising:

means for generating a combined signal from a first signal received at a first RF port (first received signal) and a second signal received at a second RF port (second received signal); and

means for generating a digital signal from the combined signal, the means for generating the digital signal including means for detecting peaks from the combined signal and means for comparing a version of the combined signal to a version of the detected peaks.

12. The device of claim 10, further comprising:

means for generating a first processed signal from the first received signal, and

wherein the first processed signal is used to generate the combined signal.

14. The device of claim 12, wherein

the means for generating the first processed signal includes an envelope detector.

11. A device for use in an RFID tag comprising:

means for generating a combined signal from a first signal received at a first RF port (first received signal) and a second signal received at a second RF port (second received signal); and

means for generating a digital signal from the combined signal, the means for generating the digital signal including means for detecting an average value of the combined signal and means for comparing a version of the combined signal to a version of the detected average value.

13. The device of claim 11, further comprising:

means for generating a first processed signal from the first received signal, and

wherein the first processed signal is used to generate the combined signal.

15. The device of claim 13, wherein

the means for generating the first processed signal includes an envelope detector.

16. A device for use in an RFID tag comprising:

means for receiving a first signal at a first RF port (first received signal);

means for receiving a second signal at a second RF port (second received signal);

means for generating a first processed signal from the first received signal, the means for generating a first processed signal including a first envelope detector;

means for generating a second processed signal from the second received signal, the means for generating the second processed signal including a second envelope detector;

means for generating a combined signal from the first processed signal and the second processed signal; and

means for generating a digital signal from the combined signal.

17. The device of claim 16, wherein

the means for generating the combined signal includes an adder.

18. A method for using a circuit of an RFID tag, comprising:

receiving a first signal at a first RF port (first received signal);

receiving a second signal at a second RF port (second received signal);

generating a combined signal from the first received signal and the second received signal; and

generating a digital signal from the combined signal, the digital signal being generated by detecting peaks from the combined signal and comparing a version of the combined signal to a version of the detected peaks.

20. The method of claim 18, further comprising:

generating a first processed signal from the first received signal; and

wherein the generating the combined signal includes

using the first processed signal to generate the combined signal.

22. The method of claim 20, wherein

the generating the first processed signal is performed by detecting an envelope of the first received signal.

24. The method of claim 22, further comprising:

generating a second processed signal from the second received signal; and

wherein the generating the combined signal includes using the second processed signal to generate the combined signal.

26. The method of claim 24, wherein

the generating a combined signal includes adding the first processed signal and the second processed signal.

28. The method of claim 26, wherein

the generating a combined signal is performed at a node.

30. The method of claim 28, further comprising:

storing charge at the node.

32. The method of claim 30, further comprising:

discharging charge from the charge stored at the node.

19. A method for using a circuit of an RFID tag, comprising:

receiving a first signal at a first RF port (first received signal);

receiving a second signal at a second RF port (second received signal);

generating a combined signal from the first received signal and the second received signal; and

generating a digital signal from the combined signal, the digital signal being generated by detecting an average value of the combined signal and comparing a version of the combined signal to a version of the detected average value.

21. The method of claim 19, further comprising:

generating a first processed signal from the first received signal; and

wherein the generating the combined signal includes using the first processed signal to generate the combined signal.

23. The method of claim 21, wherein

the generating the first processed signal is performed by detecting an envelope of the first received signal.

25. The method of claim 23, further comprising:

generating a second processed signal from the second received signal; and

wherein the generating the combined signal includes using the second processed signal to generate the combined signal.

27. The method of claim 25, wherein

the generating a combined signal includes adding the first processed signal and the second processed signal.

29. The method of claim 27, wherein

the generating a combined signal is performed at a node.

31. The method of claim 29, further comprising:

storing charge at the node.

33. The method of claim 31, further comprising:

discharging charge from the charge stored at the node.