# US 8,464,957 B2 · Integrated circuits with persistent data storage

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- Number: US 8,464,957 B2
- Document ID: US8464957B2
- Status: Granted
- Kind: B2
- Application number: 13/276,222
- Filed: 2011-10-18
- Published: 2012-06-14
- Granted: 2013-06-18
- Earliest claimed: 2001-05-31
- Assignees: Alien Technology Corporation
- Applicants: Curtis L. Carrender; Roger G. Stewart; John H. Rolin; Ronald Gilbert
- Inventors: Curtis L. Carrender; Roger G. Stewart; John H. Rolin; Ronald Gilbert
- Web page: https://patentgrep.com/patent/US8464957B2

## CPC

- 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}
- G06K 7/10019: {resolving collision on the communication channels between simultaneously or concurrently interrogated record carriers. (collision between the communication channels used by wireless communication devices, where the solution is not particularly adapted for RFIDs or the like, H04W74/08)}
- G06K 19/07381: {with deactivation or otherwise incapacitation of at least a part of the circuit upon detected tampering}
- G06K: GRAPHICAL DATA READING (image or video recognition or understanding G06V); PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS

## Abstract

A tag receives a first code transmitted by an RFID reader. The first code is compared with a second code stored within the tag. If the first code and the second code match, the tag transmits a third code to the RFID reader.

## Claims

### Claim 1

A method for a radio frequency identification (RFID) tag comprising:
receiving a first code transmitted by an RFID reader, the first code generated by an XOR calculation;
comparing a second code within the tag to the first code;
and
if the first code and second code match, transmitting by the tag a third code to the RFID reader.

### Claim 2 (depends on 1)

The method of claim 1 wherein the third code is a CRC code and wherein the first code is an access code and wherein the method further comprises:
if the first code and second code do not match, muting the tag.

### Claim 3 (depends on 1)

The method of claim 1 wherein the tag includes read only memory.

### Claim 4 (depends on 1)

The method of claim 1 wherein the tag includes a dipole antenna.

### Claim 5 (depends on 1)

The method of claim 1 wherein the tag includes a loop antenna.

### Claim 6 (depends on 1)

The method of claim 1 wherein the tag is configured for a half-duplex communication under a reader talks first protocol.

### Claim 7 (depends on 1)

The method of claim 1 wherein the tag is a passive tag.

### Claim 8 (depends on 1)

The method of claim 1 wherein the tag includes a battery.

### Claim 9 (depends on 1)

The method of claim 1 wherein the receiving is within a 902 MHz to 928 MHz band.

### Claim 10 (depends on 1)

The method of claim 1 wherein the tag includes a tenacious node.

### Claim 11

A method for a passive radio frequency identification (RFID) tag comprising:
receiving an access code transmitted by a reader, the access code generated by an XOR calculation;
comparing a second code within the passive RFID tag to the access code;
and
if the access code and second codes match, transmitting by the passive RFID tag a CRC code to the reader.

### Claim 12 (depends on 11)

The method of claim 11 wherein the passive RFID tag is configured for a half-duplex, reader talks first protocol and wherein the method further comprises if the access code and the second code do not match, muting the passive RFID tag.

### Claim 13 (depends on 11)

The method of claim 11 wherein the tag includes a tenacious node and wherein the passive RFID tag includes a dipole antenna.

### Claim 14

A radio frequency identification (RFID) system comprising:
a receiver configured to receive a first code transmitted by an RFID reader, the first code generated by an XOR calculation;
a backscatter transmitter;
processing logic coupled to the backscatter transmitter and to the receiver and configured to compare a second code within the system to the first code and configured to cause the backscatter transmitter to transmit a third code to the RFID reader if the first code and the second code match.

### Claim 15 (depends on 14)

The system as in claim 14 further comprising an antenna, wherein the antenna is a dipole antenna and the processing logic is configured for a half-duplex communication under a reader talks first protocol.

### Claim 16 (depends on 15)

The system as in claim 15 further comprising:
a tenacious node coupled to the processing logic.

### Claim 17 (depends on 14)

The system as in claim 14, wherein the system comprises a loop antenna.

### Claim 18 (depends on 14)

The system as in claim 14, wherein the system comprises a read only memory.

### Claim 19

A radio frequency identification (RFID) reader comprising:
at least one antenna;
a receiver coupled to the at least one antenna;
a transmitter coupled to the at least one antenna;
processing logic coupled to the transmitter and configured to cause the transmitter to transmit an access code that is generated by an XOR calculation and configured to receive a response which includes a CRC code from a tag in response to the access code wherein the processing logic is configured for a half-duplex communication under a reader talks first protocol.