Radio frequency identification architecture

• US 6,989,750 B2
• Filed: 02/12/2002
• Issued: 01/24/2006
• Est. Priority Date: 02/12/2001
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Bandy, William R., Powell, Kevin J., Shanks, Wayne E., Arneson, Michael R.
• Primary Examiner(s): TRIEU, VAN THANH
• Application Number:
  US10/072,984
• Publication Number:
  US 20020167405A1
• Time in Patent Office: 1,442 Days
• Field of Search: 340/272.1, 340/272.4, 340/272.7, 327/536, 327/537, 341/53
• US Class Current: 340/572.4
• CPC Class Codes: G06K 17/00 Methods or arrangements for effecting co-operative working between equipments covered by two or more of main groups G06K1/00 - G06K15/00, e.g. automatic card files incorporating conveying and reading operations
• CPC Class Codes: G06K 19/0713 the arrangement including a power charge pump
• 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
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10039 interrogator driven, i.e. synchronous
• CPC Class Codes: G06K 7/10069 the collision being resolved in the frequency domain, e.g. by hopping from one frequency to the other frequency hopping or spread spectrum techniques H04B7/00
• CPC Class Codes: G06K 7/10108 interrogating only those RFIDs that fulfill a predetermined requirement, e.g. selecting all RFIDs having the same speed and moving in a cloud like fashion, e.g. on the same train; interrogating only RFIDs having a certain predetermined temperature, e.g. in the same fridge, another possibility being the active ignoring of a group of tags that fulfill a predetermined requirement, equivalent to the Boolean NOT operation
• CPC Class Codes: G06K 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas
• CPC Class Codes: G08B 13/2485 Simultaneous detection of multiple EAS tags
• CPC Class Codes: G11C 5/142 Contactless power supplies, e.g. RF, induction, or IR
• CPC Class Codes: H04L 7/0331 with a digital phase-locked loop [PLL] processing binary samples, e.g. add/subtract logic for correction of receiver clock H04L7/0337 takes precedence

Abstract

A radio frequency identification (RFID) architecture is described. RFID tags are interrogated by a reader, which may be located in a network of readers. The reader transmits symbols to the tags. Tags respond to the interrogations with symbols that each represent one or more bits of data. An RFID tag includes an antenna pad, a receiver, a state machine, and a modulator. The receiver is coupled to the antenna pad. The receiver receives a symbol from the antenna pad and outputs a received signal. The state machine is configured to determine a response symbol from the received signal and an operating state of the tag. The modulator is coupled to the antenna pad. The modulator is configured to backscatter modulate the received symbol with the response symbol. The modulator is configured to output the backscatter modulated symbol to the antenna pad.

Claims

1. A radio frequency identification (RFID) integrated circuit (IC), comprising:

a first antenna pad;

a second antenna pad;

a first modulator coupled to said first antenna pad, wherein said first modulator is configured to backscatter modulate a first symbol received from said first antenna pad with a response symbol, wherein said first modulator is configured to output said backscatter modulated first symbol to said first antenna pad;

a second modulator coupled to said second antenna pad, wherein said second modulator is configured to backscatter modulate a second symbol received from said second antenna pad with the response symbol, wherein said second modulator is configured to output said backscatter modulated second symbol to said second antenna pad;

a first charge pump coupled to said first antenna pad, said first charge pump configured to convert a first high frequency signal from said first antenna pad to a first substantially direct current (DC) voltage; and

a second charge pump coupled to said second antenna pad, said second charge pump configured to convert a second high frequency signal from said second antenna pad to a second substantially direct current (DC) voltage.

2. The RFID IC of claim 1, further comprising:

a first receiver coupled to said first antenna pad, wherein said first receiver receives said first symbol from said first antenna pad and outputs a first received signal; and

a second receiver coupled to said second antenna pad, wherein said second receiver receives said second symbol from said second antenna pad and outputs a second received signal.

3. The RFID IC of claim 2, further comprising:

a state machine configured to receive said first received signal and said second received signal and generate said response symbol.

4. The RFID IC of claim 3, further comprising:

a data programming unit that stores a tag identification number.

5. The RFID IC of claim 4, wherein said state machine is configured to read said stored tag identification number, wherein said state machine is configured to generate said response symbol using said first received signal, said second received signal, and a bit of said read tag identification number.

6. The RFID IC of claim 1, further comprising:

a node at which said first substantially DC voltage signal and said second substantially DC voltage signal are coupled together.

7. The RFID IC of claim 6, further comprising:

a power bus coupled to said node to route power to one or more components of the RFID IC.

8. The RFID IC of claim 1, further comprising:

means for storing a bit pattern.

9. The RFID IC of claim 1, further comprising:

a first data recovery circuit coupled to said first antenna pad, said first data recovery circuit configured to demodulate said first high frequency signal to a first demodulated signal; and

a second data recovery circuit coupled to said second antenna pad, said second data recovery circuit configured to convert said second high frequency signal to a second demodulated signal.

10. The RFID IC of claim 9, wherein said first data recovery circuit comprises a first demodulator circuit configured to detect an amplitude envelope of said first high frequency signal, and wherein said second data recovery circuit comprises a second demodulator circuit configured to detect an amplitude envelope of said second high frequency signal.

11. The RFID IC of claim 9, wherein said first demodulated signal and said second demodulated signal are combined according to a logical OR function to output a digital information signal.

12. The RFID IC of claim 9, wherein said first demodulated signal and said second demodulated signal are combined as analog signals.

13. A radio frequency identification (RFID) tag device, comprising:

a first antenna;

a second antenna;

a first receiver coupled to said first antenna, wherein said first receiver is configured to receive a first symbol from said first antenna, and wherein said first receiver is configured to generate a first received signal;

a first modulator coupled to said first antenna, wherein said first modulator is configured to backscatter modulate the received first symbol with a response symbol, wherein said backscatter modulated first symbol is output to said first antenna;

a first charge pump coupled to said first antenna, said first charge pump configured to convert a first high frequency signal from said first antenna to a first substantially direct current (DC) voltage;

a second receiver coupled to said second antenna, wherein said second receiver is configured to receive a second symbol from said second antenna, and wherein said second receiver is configured to generate a second received signal;

a second modulator coupled to said second antenna, wherein said second modulator is configured to backscatter modulate the received second symbol with the response symbol, wherein said backscatter modulated second symbol is output to said second antenna;

a second charge pump coupled to said second antenna, said second charge pump configured to convert a second high frequency signal from said second antenna to a second substantially direct current (DC) voltage; and

a state machine coupled to said data programming unit and said first and said second receivers.

14. The RFID tag device of claim 13, wherein said state machine is configured to receive said first received signal from said first receiver and to receive said second received signal from said second receiver, wherein said state machine generates said response symbol.

15. The RFID tag device of claim 14, further comprising:

a data programming unit that stores a tag identification number.

16. The RFID tag device of claim 15, wherein said state machine is configured to read said stored tag identification number, wherein said state machine is configured to generate said response symbol using said received signal and a bit of said read tag identification number.

17. The RFID tag device of claim 13, further comprising:

a node at which said first substantially DC voltage signal and said second substantially DC voltage signal are coupled together.

18. The RFID tag device of claim 17, further comprising:

a power bus coupled to said node to route power to at least said state machine.

19. The RFID tag device of claim 17, further comprising:

means for communicating with a reader using a binary traversal algorithm, said binary traversal algorithm comparing bits within the bit pattern to symbols received from said reader.

20. The RFID tag device of claim 13, further comprising:

means for storing a bit pattern.

21. The RFID tag device of claim 13, further comprising:

a substrate having an input capable of receiving a high frequency signal;

wherein said first antenna and said second antenna are disposed on said substrate.