RFID tag circuits with floating differential inputs

• US 9,142,881 B1
• Filed: 06/12/2009
• Issued: 09/22/2015
• Est. Priority Date: 08/29/2008
• Status: Active Grant

• Current Assignee: Impinj, Inc.
• Original Assignee: Impinj, Inc.
• Inventors: Oliver, Ronald A., Heinrich, Harley K., Diorio, Christopher J.
• Primary Examiner(s): Lim, Steven
• Assistant Examiner(s): Adnan, Muhammad
• Application Number:
  US12/483,842
• Time in Patent Office: 2,293 Days
• Field of Search: 3405721-5729
• US Class Current: 1/1
• 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 19/0724 the arrangement being a circuit for communicating at a plurality of frequencies, e.g. for managing time multiplexed communication over at least two antennas of different types
• CPC Class Codes: G06K 19/07766 comprising at least a second communication arrangement in addition to a first non-contact communication arrangement
• 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
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H01Q 1/248 provided with an AC/DC converting device, e.g. rectennas
• CPC Class Codes: H01Q 21/30 Combinations of separate antenna units operating in different wavebands and connected to a common feeder system
• CPC Class Codes: H04Q 2213/095 User access; PIN code

Abstract

An Integrated Circuit (IC) for an RFID tag and a tag including such an IC are provided where the IC includes at least two rectifiers and two antenna ports for connecting to two respective antennas with at least three of the four antenna terminals not sharing a reference potential of the IC. According to other embodiments, the antenna ports are also electrically isolated from each other.

Claims

1. An Integrated Circuit (IC) for a Radio Frequency Identification (RFID) tag configured to communicate with an RFID reader, the IC comprising:

a first input coupled to a first rectifier and comprising a first IC terminal and a second IC terminal;

wherein

the first IC terminal is coupled to the first rectifier through a first coupling capacitor; and

the second IC terminal is coupled to the first rectifier through a second coupling capacitor; and

a second input coupled to a second rectifier and comprising a third IC terminal and a fourth IC terminal;

wherein

the third IC terminal is coupled to the second rectifier through a third coupling capacitor; and

the fourth IC terminal is coupled to the second rectifier;

wherein

the first input and the second input are not directly coupled to and do not share a common reference potential on the IC prior to or at their respective couplings to the first and second rectifiers, such that an odd-mode excitation signal at the first input results in substantially no coupling of the signal to the second input through the IC.

2. The IC of claim 1, further including a reference potential, and wherein at least three of the four IC terminals are disconnected from the reference potential.

3. The IC of claim 1, wherein the first and second inputs form an X configuration of the IC terminals.

4. The IC of claim 1, wherein a first antenna is coupled to the first input and a second antenna is coupled to the second input.

5. The IC of claim 4, wherein the first antenna is a near-field antenna and the second antenna is a far-field antenna.

6. The IC of claim 4, wherein both the first and second antennas are far-field antennas.

7. The IC of claim 2, further including a power management unit (PMU), wherein at least one of the first and second rectifiers is coupled to the PMU, and the PMU is coupled to the reference potential.

8. The IC of claim 2, wherein the first and second rectifiers are coupled to the reference potential.

9. The IC of claim 1, in which the fourth IC terminal is also disconnected from the reference potential.

10. An Integrated Circuit (IC) for a Radio Frequency Identification (RFID) tag configured to communicate with an RFID reader, the IC comprising:

a first input coupled to a first rectifier and comprising a first IC terminal and a second IC terminal;

wherein

the first IC terminal is coupled to the first rectifier through a first coupling capacitor; and

the second IC terminal is coupled to the first rectifier through a second coupling capacitor; and

a second input coupled to a second rectifier and comprising a third IC terminal and a fourth IC terminal;

wherein

the third IC terminal is coupled to the second rectifier through a third coupling capacitor; and

the fourth IC terminal is coupled to the second rectifier through a fourth coupling capacitor;

wherein

the first input and the second input are not directly coupled to and do not share a common reference potential on the IC prior to or at their respective couplings to the first and second rectifiers, such that an odd-mode excitation signal at the first input results in substantially no coupling of the signal to the second input through the IC.

11. The IC of claim 10, wherein at least one of the first, second, third, and fourth coupling capacitors is located on the IC.

12. The IC of claim 10, wherein at least one of the first, second, third, and fourth coupling capacitors is located off the IC.

13. A Radio Frequency Identification (RFID) tag configured to communicate with an RFID reader, the tag comprising:

a first antenna and a second antenna; and

an integrated circuit (IC) including;

a first input coupled to the first antenna and to a first rectifier, and comprising a first IC terminal and a second IC terminal;

wherein

the first IC terminal is coupled to the first rectifier through a first coupling capacitor; and

the second IC terminal is coupled to the first rectifier through a second coupling capacitor; and

a second input coupled to the second antenna and to a second rectifier, and comprising a third IC terminal and a fourth IC terminal;

wherein

the third IC terminal is coupled to the second rectifier through a third coupling capacitor; and

the fourth IC terminal is coupled to the second rectifier;

wherein

the first input and the second input are not directly coupled to and do not share a common reference potential on the IC prior to or at their respective couplings to the first and second rectifiers, such that an odd-mode excitation signal at the first input results in substantially no coupling of the signal to the second input through the IC.

14. The RFID tag of claim 13, further including a reference potential, wherein at least three of the IC terminals are disconnected from the reference potential.

15. The tag of claim 13, wherein the first antenna is a far-field antenna and the second antenna is one of a near-field antenna and a far-field antenna.

16. The tag of claim 14, further including a power management unit (PMU), and wherein:

the first and second rectifiers are coupled to the reference potential;

at least one of the first and second rectifiers is coupled to the PMU; and

the PMU is coupled to the reference potential.

17. A Radio Frequency Identification (RFID) tag configured to communicate with an RFID reader, the tag comprising:

a first antenna and a second antenna; and

an integrated circuit (IC) including;

a first input to the IC coupled to the first antenna and to a first rectifier, and comprising a first IC terminal and a second IC terminal;

wherein

the first IC terminal is coupled to the first rectifier through a first coupling capacitor; and

the second IC terminal is coupled to the first rectifier through a second coupling capacitor; and

a second input to the IC coupled to the second antenna and to a second rectifier, and comprising a third IC terminal and a fourth IC terminal;

wherein

the third IC terminal is coupled to the second rectifier through a third coupling capacitor; and

the fourth IC terminal is coupled to the second rectifier through a fourth coupling capacitor;

wherein

the first input and the second input are not directly coupled to and do not share a common reference potential on the IC prior to or at their respective couplings to the first and second rectifiers, such that an odd-mode excitation signal at the first input results in substantially no coupling of the signal to the second input through the IC.

18. The tag of claim 17, wherein the first and second antennas are configured such that the tag is substantially responsive to an electromagnetic field regardless of its orientation to the electromagnetic field.

19. The tag of claim 17, wherein the first and second antennas comprise crossed dipoles sharing a common loop.