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

• US 7,068,173 B2
• Filed: 05/07/2004
• Issued: 06/27/2006
• 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: Shanks, Wayne E., Bandy, William R., Powell, Kevin J., Arneson, Michael R.
• Primary Examiner(s): TRIEU, VAN THANH
• Application Number:
  US10/840,790
• Publication Number:
  US 20040207527A1
• Time in Patent Office: 781 Days
• Field of Search: 340/572.1, 340/572.2, 340/572.4, 340/572.5, 340/572.7, 340/10.3, 340/10.4, 340/10.41, 340/10.33, 235/462.45, 235/426.46, 370/277
• 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. A method of operating an identification tag, comprising:

receiving a radio frequency (RF) signal;

converting said RF signal to a direct current (DC) voltage;

providing a power supply for the identification tag based on said DC voltage from said converting step;

recovering data from said RF signal; and

reflecting said RF signal in response to a control signal that identifies said identification tag, including the step of shorting said RF signal to ground in accordance with a control signal that identifies said identification tag.

2. The method of claim 1, wherein said step of recovering data from said RF signal is performed in parallel with said step of converting said RF signal to a DC voltage.

3. The method of claim 1, wherein said step of recovering data from said RF signal is performed substantially simultaneously with said step of converting said RF signal to a DC voltage.

4. The method of claim 1, wherein said step of providing comprises the step of providing a power supply based on said DC voltage to perform said step of recovering data.

5. The method of claim 1 wherein said step of receiving a RF signal comprises the step of receiving a RF signal transmitted from a tag reader.

6. The method of claim 5, wherein said RF signal includes polling data for the identification tag.

7. The method of claim 1, wherein said step of providing a power supply includes the step of coupling said DC voltage to a data recovery circuit of the identification tag.

8. The method of claim 1, wherein said step of providing a power supply includes the step of coupling said DC voltage to a state machine of the identification tag.

9. The method of claim 1, wherein said step of providing a power supply includes the step of coupling said DC voltage to a backscatter switch of the identification tag.

10. The method of claim 1, further comprising the step of transmitting said reflected RF signal to a tag reader.

11. The method of claim 1, further comprising the step of reducing an efficiency of said converting step if said DC voltage exceeds a threshold voltage.

12. The method of claim 1, further comprising the step of conducting charge from said DC voltage to ground when said DC voltage exceeds a threshold voltage.

13. The method of claim 1, wherein said step of converting includes the step of accumulating charge over multiple cycles of said RF signal to generate said DC voltage.

14. A method of operating an identification tag, comprising:

receiving a radio frequency (RF) signal;

converting said RF signal to a direct current (DC) voltage;

providing a power supply for the identification tag based on said DC voltage from said converting step; and

recovering data from said RF signal;

wherein said step of converting includes the step of shunting charge to ground when said DC voltage reaches a threshold.

15. In an identification tag having a data recovery circuit, a method, comprising:

receiving multiple cycles of a radio frequency (RF) signal;

accumulating charge over said multiple cycles of said RF signal to generate a DC voltage;

providing said DC voltage as a power supply for said data recovery circuit; and

shunting charge to ground when said DC voltage exceeds a threshold.

16. The method of claim 15, further comprising the step of:

recovering data from said RF signal using said data recovery circuit.

17. The method of claim 16, wherein said step of recovering data is performed in parallel with said step of providing said DC voltage.

18. The method of claim 16, wherein said step of recovering data is performed simultaneously with said step of providing said DC voltage.

19. The method of claim 15, wherein said identification tag includes a state machine, the method further comprising the step of providing said DC voltage as a power supply for said state machine.

20. The method of claim 15, wherein said identification tag includes a backscatter switch, the method further comprising the step of providing said DC voltage as a power supply for said backscatter switch.

21. The method of claim 20, further comprising the step of shunting said RF signal to ground using said backscatter switch.

22. In an identification tag having a data recovery circuit and a backscatter switch, a method, comprising:

receiving multiple cycles of a radio frequency (RF) signal;

accumulating charge over said multiple cycles of said RF signal to generate a DC voltage;

providing said DC voltage as a power supply for said data recovery circuit and said backscatter switch; and

shunting said RF signal to ground using said backscatter switch;

wherein said step of shunting includes the step of shunting said RF signal to ground according to a control signal that identifies said identification tag.

23. A method of operating an identification tag, comprising:

receiving a radio frequency (RF) signal from a tag reader;

converting said RF signal to a direct current (DC) voltage;

recovering data from said RF signal using said DC voltage as a power supply; and

transmitting a backscatter signal to said tag reader using said DC voltage as a power supply;

wherein said step of transmitting includes the step of modulating an impedance of an antenna on the identification tag according to a control signal that identifies said identification tag to generate said backscattered signal.

24. The method of claim 23, wherein said backscatter signal identifies said identification tag.

25. The method of claim 23, wherein said step of transmitting includes the step of shunting said RF signal to ground according to a control signal that identifies said identification tag to generate said backscatter signal.

26. The method of claim 23, wherein said step of recovering data includes the steps of:

determining an amplitude envelope of said RF signal;

determining a reference signal of said RF signal that represents an average of said amplitude envelope over time; and

comparing said amplitude envelope with said reference signal to detect data transitions.

27. The method of claim 23, wherein said step of converting, said step of recovering, and said step of transmitting are performed in parallel with each other.

28. The method of claim 27, wherein said step of converting, said step of recovering, and said step of transmitting are performed substantially simultaneously with each other.

29. A method of operating an identification tag, comprising:

receiving multiple cycles of a radio frequency (RF) signal;

accumulating charge over said multiple cycles of the RF signal to generate a DC voltage;

providing said DC voltage as a power supply for said identification tag; and

shunting charge to ground when said DC voltage exceeds a threshold.

30. The method of claim 29, wherein said step of providing comprises:

providing said DC voltage as a power supply for a data recovery circuit on said identification tag.

31. The method of claim 29, wherein said step of providing comprises:

providing said DC voltage as a power supply for a state machine on said identification tag.

32. The method of claim 29, wherein said step of providing comprises:

providing said DC voltage as a power supply for a backscatter switch on said identification tag.