Identification tag utilizing charge pumps for voltage supply generation and data recovery

• US 6,734,797 B2
• Filed: 02/12/2002
• Issued: 05/11/2004
• Est. Priority Date: 02/12/2001
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Matrics Incorporated (Zebra Technologies Corporation)
• Inventors: Bandy, William R., Powell, Kevin J., Shanks, Wayne E., Arneson, Michael R.
• Primary Examiner(s): TRIEU, VAN THANH
• Application Number:
  US10/072,985
• Publication Number:
  US 20020149482A1
• Time in Patent Office: 819 Days
• Field of Search: 340/572.1, 340/572.2, 340/572.4, 340/572.5, 340/572.7, 340/10.3, 340/10.33, 340/10.4, 327/536, 327/537, 42/700.1, 42/700.4, 42/700.5, 342/42, 342/44, 342/51
• 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

An identification (ID) tag includes a substrate having an input capable of receiving a high frequency signal. For instance, the high frequency signal can be a radio frequency (RF) signal that is generated as part of a radio frequency (RF) ID system. A first charge pump is coupled to the input and is configured to convert the high frequency signal to a substantially direct current (DC) voltage. A data recovery circuit is coupled to the input and is capable of recovering data from the high frequency signal. A back scatter switch is coupled to the input and is capable of modifying an impedance of the input, responsive to a control signal. A state machine is disposed on the substrate and is responsive to the data recovered by the second charge pump, where the state machine is capable of generating the control signal for the back scatter switch in response to the data. The DC voltage from the first charge pump is capable of providing a voltage supply for at least one of the data recovery circuit, the back scatter switch, and the state machine. The data recovery circuit includes a second charge pump that is capable of operating on the high frequency signal simultaneously with the first charge pump. In other words, the first charge pump can generate the supply voltage for the ID tag from the high frequency signal, while the second charge pump simultaneously retrieves the data from the high frequency signal. The first charge pump also includes a means for limiting the amplitude of the DC voltage by reducing the charge pump efficiency, once a threshold voltage is reached.

Claims

1. An analog front-end for an identification tag, comprising:

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

a first charge pump coupled to said input and disposed on said substrate, said first charge pump configured to convert said high frequency signal to a substantially direct current (DC) voltage; and

a second charge pump coupled to said input and disposed on said substrate, said second charge pump capable of recovering data from said high frequency signal.

2. The analog front-end of claim 1, said DC voltage from said first charge pump capable of providing a voltage supply for said second charge pump.

3. The analog front-end of claim 1, further comprising a back scatter switch disposed on said substrate and coupled to said input, said back scatter switch configured to reflect said high frequency signal in response to a modulated signal received by said back scatter switch.

4. The analog front of claim 3, said DC voltage capable of providing a voltage supply for said back scatter switch.

5. The analog front-end of claim 1, further comprising a state machine disposed on said substrate and configured to receive said data recovered from said high frequency signal.

6. The analog front-end of claim 5, said DC voltage capable of providing a voltage supply for operation of said state machine.

7. The analog front of claim 1, said first charge pump and second charge pump capable operating simultaneously on said high frequency signal.

8. The analog front-end of claim 1, said first charge pump including a means for reducing an efficiency of said first charge pump in response to an amplitude of said DC voltage.

9. The analog front-end of claim 8, wherein said means for reducing an efficiency of said charge pump includes at least one diode having a threshold voltage that is based on a threshold amplitude of said DC voltage.

10. The analog front-end of claim 8, wherein said means for reducing an efficiency of said first charge pump includes a metal oxide semiconductor field effect transistor (MOSFET) device having a threshold voltage based on said threshold amplitude of said DC voltage.

11. The analog front-end of claim 8, wherein said means for reducing efficiency comprises a means for conducting charge away from said first charge pump to ground, and responsive to said threshold amplitude of said DC voltage.

12. The analog front-end of claim 8, wherein said means for reducing an efficiency of said first charge pump includes a means for mismatching said input.

13. An identification (ID) tag, comprising:

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

a first charge pump coupled to said input and disposed on said substrate, said first charge pump configured to convert said high frequency signal to a substantially direct current (DC) voltage;

a data recovery circuit coupled to said input and disposed on said substrate, said data recovery having a second charge pump capable of recovering data from said high frequency signal;

a back scatter switch coupled to said input and disposed on said substrate, said back scatter switch capable of modifying an impedance of said input and responsive to a control signal; and

a state machine disposed on said substrate and responsive to said data recovered by said data recovery circuit, said state machine generating said control signal for said back scatter switch in response to said data;

said DC voltage from said first charge pump capable for providing a voltage supply for at least one of said data recovery circuit, said back scatter switch, and said state machine.

14. The ID tag of claim 13, said first charge pump having a means for limiting an amplitude of said DC voltage.

15. The ID tag of claim 14, wherein said means for limiting includes a means for conducting charge away from said first charge pump to ground when said amplitude of said DC voltage exceeds a threshold.

16. The ID tag of claim 13, wherein said substrate is implemented using a complementary metal oxide semiconductor (CMOS) process.

17. The ID tag of claim 13, wherein said DC voltage is capable of providing a voltage supply for each of said data recovery circuit, said back scatter switch, and said state machine.

18. The ID tag of claim 13, further comprising an antenna coupled to said input.

19. The ID tag of claim 18, wherein said antenna is external to said substrate.

20. The ID tag of claim 18, wherein said antenna is disposed on said substrate.

21. An analog front-end, comprising:

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

a charge pump coupled to said input and disposed on said substrate, said charge pump configured to convert said high frequency signal to a substantially direct current (DC) voltage;

said charge pump having a means for limiting an amplitude of said DC voltage, wherein said means for limiting includes a means for conducting charge away from said charge pump to ground when said amplitude of said DC voltage exceeds a threshold.

22. The analog front-end of claim 21, said means for limiting including a means for reducing an efficiency of said charge pump in response to an amplitude of said DC voltage.

23. The analog front-end of claim 21, wherein said means for conducting charge away from said charge pump includes at least one diode having a threshold voltage that is based on a threshold amplitude of said DC voltage.

24. The analog front-end of claim 23, wherein said diode includes a metal oxide semiconductor field effect transistor (MOSFET) device having a threshold voltage based on said threshold amplitude of said DC voltage.

25. An analog front-end, comprising:

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

a charge pump coupled to said input and disposed on said substrate, said charge pump configured to retrieve data from said high frequency signal; and

means for generating a reference signal from said data.

26. The analog front-end of claim 25, further comprising a means for comparing said reference signal to said data, to detect data transitions in said data.

27. The analog front-end of claim 25, wherein said means for generating comprises:

a peak detector circuit, coupled to an output of said charge pump, said peak detector configured to generate said reference signal from data signal.