RFID tags combining signals received from multiple RF ports

• US 7,423,539 B2
• Filed: 08/26/2005
• Issued: 09/09/2008
• Est. Priority Date: 03/31/2004
• Status: Active Grant

• Current Assignee: Impinj, Inc.
• Original Assignee: Impinj, Inc.
• Inventors: Oliver, Ronald A., Hyde, John D., Onen, Omer
• Primary Examiner(s): Lieu; Julie
• Application Number:
  US11/213,632
• Publication Number:
  US 20060049917A1
• Time in Patent Office: 1,110 Days
• Field of Search: 340/572.4, 340/572.1, 340/653, 340/660, 340/661
• US Class Current: 340/572.4
• 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 for receiving a first signal;

a second RF port for receiving a second signal;

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

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

wherein the signal combiner includes

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

a second envelope detector for generating a second processed signal from the second received signal, and

an adder to generate the combined signal from the first processed signal and the second processed signal.

2. The circuit of claim 1, wherein

the adder is adapted 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 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 and a second signal received at a second RF port; and

means for generating a digital signal from the combined signal,

wherein the means for generating the digital signal includes

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.

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 and a second signal received at a second RF port; and

means for generating a digital signal from the combined signal,

wherein the means for generating the digital signal includes

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.

12. 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 and a second signal received at a second RF port;

means for generating a digital signal from the combined signal;

means for generating a first processed signal from the first received signal, wherein the first processed signal is used to generate the combined signal and

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

13. 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 and a second signal received at a second RF port;

means for generating a digital signal from the combined signal wherein the means for generating the digital signal includes an adder;

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

wherein the first processed signal is used to generate the combined signal; and

means for generating a second processed signal from the second received signal,

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

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

receiving a first signal at a first RF port;

receiving a second signal at a second RF port;

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

generating a digital signal from the combined signal,

wherein the digital signal is generated by

detecting peaks from the combined signal, and

comparing a version of the combined signal to a version of the detected peaks.

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

receiving a first signal at a first RF port;

receiving a second signal at a second RF port;

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

generating a digital signal from the combined signal,

wherein the digital signal is 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.

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

receiving a first signal at a first RF port;

receiving a second signal at a second RF port;

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

generating a digital signal form the combined signal;

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

using the first processed signal to generate the combined signal,

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

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

receiving a first signal at a first RF port;

receiving a second signal at a second RF port;

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

generating a digital signal from the combined signal;

generating a second processed signal from the second received signal;

using the second processed signal to generate the combined signal;

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

using the first processed signal to generate the combined signal,

wherein the combined signal is generated at a node.

18. The method of claim 17, wherein

combining is performed by adding together the first processed signal and the second processed signal.