Abstract: A Radio Frequency Identification (RFID) tag IC stores an identifier and a check code. The IC determines whether the stored identifier is corrupted by comparing it to the check code. If the stored identifier does not correspond to the check code then the IC may terminate operation or indicate an error. The IC may also reconstruct the correct identifier from the check code.

Abstract: A self-jammer-cancellation circuit in an RFID system uses passive variable capacitance networks to attenuate phase-adjusted carrier signals, which are then combined with a received signal to reduce unwanted carrier signals in the received signal. The self-jammer-cancellation circuit also adjusts the passive variable capacitance networks such that the overall capacitance of each network remains constant or the overall relationship of capacitances between the networks remains constant.

Abstract: A Radio Frequency Identification (RFID) reader may be configured to endorse an RFID tag. The reader receives an identifier from the tag and challenges the tag with a challenge. After receiving a response from the tag, the reader sends a first message including at least the identifier, challenge, and response to an authenticating entity and sends a second message including at least the identifier to a certifying entity. The reader then receives a first reply from the authenticating entity and a second reply from the certifying entity. The second reply may include a certificate associated with the tag, or may identify some property of the tag or an item associated with the tag. In some embodiments, the reader may serve as the authenticating and/or certifying entity.

Abstract: Synthesized-beam RFID readers may be used to manage and provide information about RFID tag populations. In one embodiment, two or more synthesized-beam readers synthesize respective RF beams towards a tag location. The synthesized-beam readers may coordinate their pointing by means of a controller, a peer-to-peer network, or by using a master-slave arrangement. The synthesized-beam readers may coordinate their transmissions to increase the RF energy available to a tag at the pointing location.

Abstract: An RFID loss-prevention system (LPS) permits authorized items to leave a facility and may perform a security action if an unauthorized item leaves the facility. A checkout reader first authorizes an item tagged with an RFID tag to exit a facility by reading an identifier from the tag, obtaining an exit authorization, and sending the identifier to a database. A reader system configured to direct at least two beams along a facility exit path reads tagged items exiting the facility, determines at least one of a travel direction and a tag location, and uses the determination to indicate that a tag is exiting or has exited the facility. The LPS then uses the database to determine if the exiting/exited tag is authorized to leave the facility.

Abstract: A tuning circuit in an RFID tag may be used to match antenna and integrated circuit (IC) impedances to maximize the efficiency of IC power extraction from an incident RF wave. The tuning circuit, which requires less power to operate than the IC, adjusts a variable impedance to improve the impedance matching between the IC and the tag antenna and thereby increase the IC power extraction efficiency. The IC may begin operating according to a protocol when it extracts sufficient power from the RF wave or when an optimal impedance matching and power transfer is achieved.

Abstract: A reader may broadcast a refresh command to a population or subpopulation of tags and thereby refresh and extend the persistence time of a tag flag, such as an inventoried flag. The characteristics, timing, and other details of this broadcast refresh command may be determined based on the state of a reader, environmental, tag-population, and/or tag-capability conditions and parameters. The refresh command may be a Select command of the Gen2 Specification, in which case parameters of the Select command specify the refresh operation.

Abstract: RFID tags are assembled through affixing an antenna to an integrated circuit (IC) by forming one or more capacitors coupling the antenna and the IC with the dielectric material of the capacitor(s) including a non-conductive covering layer of the IC, a non-conductive covering layer of the antenna such as an oxide layer, and/or an additionally formed dielectric layer. Top and bottom plates of the capacitor(s) are formed by the antenna traces and one or more patches on a top surface of the IC.

Abstract: RFID readers transmit a Quiet Technology (QT) command to RFID tags causing at least one of the tags to transition between a private profile and a public profile. When a tag is inventoried in the private profile, it replies to the reader with contents from its private memory. When a tag is inventoried in the public profile, it replies to the reader with contents from its public memory, where the contents of the public memory may be a subset and/or modified version of the private memory contents, or entirely different altogether. The tag's profile can be switched again by another QT command from the reader, or following a loss of power at the tag. An access password and/or a short-range mechanism may be employed to allow only authorized readers to transition tag profiles or interrogate the private memory contents of tags in the public profile.

Abstract: A Radio Frequency Identification (RFID) tag IC stores an identifier and a check code. The IC determines whether the stored identifier is corrupted by comparing it to the check code. If the stored identifier does not correspond to the check code then the IC may terminate operation or indicate an error. The IC may also reconstruct the correct identifier from the check code.

Abstract: A Radio Frequency Identification (RFID) reader containing a reader key authenticates an RFID tag containing a tag key by receiving a reader challenge from a verification authority; determining a reader response based at least on the reader challenge and the reader key; sending a first message including at least the reader response but not the reader key to the verification authority; receiving a tag identifier from the tag; challenging the tag with a tag challenge; receiving a tag response based at least on the tag challenge and the tag key but not including the tag key; sending a second message including at least the tag identifier and the tag response to the verification authority; and receiving an electronically-signed reply from the verification authority. The reader validates the verification authority reply by checking the signature. The verification authority may notify a designated party if a response is incorrect.

Abstract: A Radio Frequency Identification (RFID) reader containing a reader key authenticates an RFID tag containing a tag key by receiving a reader challenge from a verification authority; determining a reader response based at least on the reader challenge and the reader key; sending a first message including at least the reader response but not the reader key to the verification authority; receiving a tag identifier from the tag; challenging the tag with a tag challenge; receiving a tag response based at least on the tag challenge and the tag key but not including the tag key; sending a second message including at least the tag identifier and the tag response to the verification authority; and receiving an electronically-signed reply from the verification authority. The reader validates the verification authority reply by checking the signature. The verification authority may notify a designated party if a response is incorrect.

Abstract: Methods and systems are described for authorizing an item with an RFID tag to leave a facility. In one embodiment, a mobile device receives or determines an exit code (EC) to write into the tag in response to providing authorizing information. The EC may be based on information stored in the tag such as the tag's item identifier or other tag information (collectively an item identifier or II), a ticket value, other information such as the OC, a mobile identity or location, or any other suitable information. Upon verification of the EC, the tagged item is allowed to leave the facility. In another embodiment, the mobile device stores an item identifier (II) associated with the tag and provides authorizing information. Upon verifying the authorizing information and confirming that the stored II corresponds to the tagged item's II, the tagged item is allowed to leave the facility.

Abstract: An RFID loss-prevention system (LPS) based on synthesized-beam readers (SBRs) permits authorized items to leave a facility and may perform a security action if an unauthorized item leaves the facility. A checkout reader first authorizes an item tagged with an RFID tag to exit a facility by reading an identifier from the tag, obtaining an exit authorization, and sending the identifier to a database. An SBR configured to direct at least two beams along a facility exit path reads tagged items exiting the facility, determines at least one of a travel direction and a tag location, and uses the determination to indicate that a tag is exiting or has exited the facility. The LPS then uses the database to determine if the exiting/exited tag is authorized to leave the facility.

Abstract: A synthesized-beam transceiver system steers a beam of a two-dimensional antenna array by activating a first subset of antenna elements to orient the beam in a first direction and subsequently activating a second subset of the antenna elements to orient the beam in a different direction. The system also electrically connects antenna elements that are inactive, not in the first subset, or not in the second subset to a reference potential of the array.

Abstract: An RFID tag is configured to adjust its current clock frequency to conserve tag power while receiving a reader signal and/or backscattering a signal. The tag may determine whether to adjust its current clock frequency based on one or more timing parameters, which may be determined from a reader command and/or from a signal to be backscattered. The counting rate and/or limit of a tag counter and/or the power supplied to a tag component may also be adjusted. The current tag clock frequency may be adjusted during the signal reception/backscattering process and optionally restored once the process is completed.

Abstract: An Integrated Circuit (IC) for an RFID tag and a tag including such an IC are provided where the IC includes at least two rectifiers and two antenna ports for connecting to two respective antennas with at least three of the four antenna terminals not sharing a reference potential of the IC. According to other embodiments, the antenna ports are also electrically isolated from each other.

Abstract: RFID reader systems, readers, components, software and methods cause RFID tags to backscatter a combination made from at least portions of a first code and a second code, without transmitting any commands in the interim. The first and/or second codes may include a tag response to a reader challenge. In a number of embodiments, a separate command does not have to be sent for reading the second code along with the first code, thereby saving time in inventorying the tags. Plus, the combination can enable reading tag codes during tag manufacturing that are not otherwise readily available to read in the field. In some embodiments, the combination may further include one or more error-checking codes.

Abstract: RFID reader systems, readers, components, software and methods cause RFID tags to backscatter a combination made from at least portions of a first code and a second code, without transmitting any commands in the interim. The first and/or second codes may include a tag response to a reader challenge. In a number of embodiments, a separate command does not have to be sent for reading the second code along with the first code, thereby saving time in inventorying the tags. Plus, the combination can enable reading tag codes during tag manufacturing that are not otherwise readily available to read in the field. In some embodiments, the combination may further include one or more error-checking codes.

Abstract: An authentication method includes RFID readers authenticating RFID tags using public-key cryptography. A tag manufacturer or other legitimate authority produces a tag private-public key pair and stores the tag private key in externally unreadable tag memory and the tag public key in externally readable tag memory. The authority produces a master private-public key pair and distributes the master public key to readers in the field. The authority generates a tag-specific electronic signature based on at least the tag public key and the master private key and stores this signature in externally readable tag memory. A reader authenticates the tag by retrieving the tag public key and electronic signature from the tag, verifying the authenticity of the tag public key using the master public key and the electronic signature, challenging the tag, receiving a response from the tag to the challenge, and verifying the response using the tag public key.