Smart card receiver and system for pulsed RF fields

• US 20060261927A1
• Filed: 05/19/2006
• Published: 11/23/2006
• Est. Priority Date: 04/01/1996
• Status: Active Grant

• Current Assignee: Cubic Corporation
• Original Assignee: Cubic Corporation
• Inventors: Kelly, Guy M., Page, Kevin J., Plum, Don P., Ravenis, Joseph VJ II
• Granted Patent: US 7,705,712 B2
• Time in Patent Office: Days
• US Class Current: 340/10.100
• CPC Class Codes: G06K 19/0701 at least one of the integrated circuit chips comprising an arrangement for power management
• 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 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 7/10059 transponder driven

Abstract

A fast data transfer collection system using message authentication and contactless RF proximity card technology in non-contact storage and retrieval applications. The system is generally comprised of Host computers (application computer systems), Target radio frequency (RF) terminals, and a plurality of portable Tags (“smart” or “proximity” cards). A Host provides specific application functionality to a Tag holder, with a high degree of protection from fraudulent use. A Target provides control of the RF antenna and resolves collisions between multiple Tags in the RF field. A Tag provides reliable, high speed, and well authenticated secure exchanges of data/information with the Host resulting from the use of a custom ASIC design incorporating unique analog and digital circuits, nonvolatile memory, and state logic. Each Tag engages in a transaction with the Target in which a sequence of message exchanges allow data to be read(written) from(to) the Tag. These exchanges establish the RF communication link, resolve communication collisions with other Tags, authenticate both parties in the transaction, rapidly and robustly relay information through the link, and ensure the integrity and incorruptibility of the transaction. The system architecture provides capabilities to ensure the integrity of the data transferred thus eliminating the major problem of corrupting data on the card and in the system. The architecture and protocol are designed to allow simple and efficient integration of the transaction product system into data/information processing installations.

Claims

1. A tag including an integrated circuit, the integrated circuit comprising:

a digital subsystem for processing data received from a target; and

an analog subsystem for receiving the data from the target through a pulsed RF field, the analog subsystem comprising a fast-clamping receiver having a shunt regulator configured to protect the integrated circuit from over-voltage transients.

wherein the shunt regulator substantially removes AM voltage fluctuations and accurately adjusts a clamping voltage to be slightly below a breakdown voltage for the integrated circuit.

2. The tag of claim 1, wherein the tag is positioned at a fixed location.

3. The tag of claim 1, wherein the analog subsystem further comprises:

a series regulator coupled with the shunt regulator and configured to;

monitor a current in the shunt regulator; and

adjust a series impedence to control the current to remain above a minimum threshold.

4. The tag of claim 3, wherein a time constant for a control loop of the series regulator is longer than a time constant for a control loop of the shunt regulator.

5. The tag of claim 3, wherein the series regulator is further configured to:

short the series impedance during data transmission from the tag.

6. The tag of claim 5, wherein the analog subsystem further comprises:

a second shunt regulator coupled with the series regulator, and configured to;

output a regulated voltage to provide a fixed modulation depth for transmitting data, wherein the regulated voltage powers the digital subsystem; and

dissipate excess current in the integrated circuit via a control loop.

7. The tag of claim 1, the tag further comprising:

a tag antenna configured to generate a voltage from the pulsed RF field.

8. The tag of claim 7, wherein substantially removing AM voltage fluctuations comprises controlling a current to modify the generated voltage thereby resulting in a substantially constant voltage output.

9. The tag of claim 7, wherein the analog subsystem further comprises:

a rectifier configured to receive an AC input and generate a DC output that includes AM voltage fluctuations,

wherein the generated voltage comprises the AC input, and

wherein the AM voltage fluctuations substantially removed by the shunt regulator comprise the AM voltage fluctuations of the DC output.

10. The tag of claim 1, wherein the integrated circuit further comprises:

a clock circuit for generating a fast mode clock signal for execution of instructions and a slow mode clock signal for data communication.

11. The tag of claim 1, wherein the shunt regulator is further configured to detect incoming data.

12. The tag of claim 1, wherein the tag comprises a smart card.

13. A method of regulating voltage of an integrated circuit in a tar, the method comprising:

generating the voltage from a pulsed RF field;

substantially removing AM voltage fluctuations from the generated voltage; and

adjusting a clamping voltage to be slightly below a breakdown voltage for the integrated circuit.

14. The method of claim 13, the method further comprising:

positioning the tag in a fixed location.

15. The method of claim 13, wherein substantially removing AM voltage fluctuations comprises:

controlling a current to modify the generated voltage thereby resulting in a substantially constant voltage output.

16. The method of claim 13, the method further comprising:

generating a DC output from an AC input, the DC output including AM voltage fluctuations,

wherein the generated voltage comprises the AC input; and

wherein substantially removing AM voltage fluctuations comprises substantially removing AM voltage fluctuations of the DC output.

17. The method of claim 13, the method further comprising:

generating a fast mode clock signal for execution of instructions of the integrated circuit; and

generating a slow mode clock signal for data communication.

18. The method of claim 13, wherein the tag comprises a smart card.

19. A contactless data collection system comprising:

a target; and

a tag positioned in a fixed location and including an integrated circuit, the integrated circuit having;

an analog subsystem for receiving the data from the target through the pulsed RF field, the analog subsystem including a fast-clamping receiver having a shunt regulator, the shunt regulator configured to substantially remove AM voltage fluctuations and to accurately adjust a clamping voltage to be slightly below a breakdown voltage for the integrated circuit; and

a clock circuit for generating a fast mode clock signal for execution of instructions and a slow mode clock signal for data communication.

20. The system of claim 19, wherein the analog subsystem further comprises:

a series regulator coupled with the shunt regulator and configured to;

monitor a current in the shunt regulator; and

adjust a series impedence to control the current to remain above a minimum threshold; and

a second shunt regulator coupled with the series regulator, and configured to

output a regulated voltage to provide a fixed modulation depth for transmitting data, wherein the regulated voltage powers the digital subsystem and

dissipate excess current in the integrated circuit via a control loop.