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.

Abstract: Embodiments are directed to a Radio Frequency Identification (RFID) integrated circuit (IC) having a first circuit block electrically coupled to first and second antenna contacts. The first antenna contact is disposed on a first surface of the IC and the second antenna contact is disposed on a second surface of the IC different from the first surface. The first and second antenna contacts are electrically disconnected from each other.

Abstract: Radio Frequency Identification (RFID) tags may receive one or more encapsulated commands within the payload of an encapsulating command from an RFID reader. An encapsulated command includes at least a command code and an instruction. A tag may store the encapsulated command(s) or the instruction portion of the encapsulated command(s) for later execution. A sequence of encapsulated commands may be contained within one encapsulating command or spread across multiple encapsulating commands. The sequence of encapsulated commands, or the sequence of instructions associated with the encapsulated commands, may form a program. The tag may execute the instructions or program upon receipt, upon a trigger event, serially or in parallel, and/or may modify the instructions or program by adjusting parameters. The tag may later be told by a reader to execute the instructions or program via another command which, in some cases, may be sent prior to tag singulation.

Abstract: An Integrated Circuit (IC) for an RFID tag includes two electrically isolated antenna ports for connecting to two antennas, with each antenna port configured to operate at a different frequency range and/or with a different communications protocol. In some embodiments a rectifier coupled to one of the antenna ports is operable to extract energy from an electromagnetic field in a first frequency range, and a demodulator coupled to the other antenna port is operable to demodulate symbols according to an RFID protocol in a second frequency range. In some embodiments the frequency ranges are disjoint, intersecting, or one is a proper subset of the other. In some embodiments each port is coupled to its own rectifier and/or its own modulator and/or its own demodulator. In some embodiments an RFID tag includes the IC and two antennas, each operable in one of the two frequency ranges.

Abstract: An RFID tag tuning circuit may be capable of adjusting the impedance matching between an RFID integrated circuit (IC) and an antenna on an RFID tag to increase the amount of power that the IC can extract from an incident RF wave. The tuning circuit switches a variable impedance coupling the antenna and the IC between several different impedance settings, where each impedance setting differs from an adjacent impedance setting by a respective impedance step size and at least one impedance step size has a different value than another impedance step size. The tuning circuit may switch the variable impedance by incrementing through a counter, decrementing through the counter, or performing some search algorithm. The tuning circuit may also initialize the variable impedance based on a default impedance setting or a random impedance setting derived from a random counter.

Abstract: Systems, methods of operation, and software are provided, for encoding RFID tags with which a predefined group of items is tagged. Encoding is by writing applicable Electronic Product Codes (EPCs) to the tags, so as to identify the individual items in the group. A base code can be read from each tag, and the applicable EPC is then written to it.

Abstract: A Radio Frequency Identification (RFID) assembly includes an IC, a repassivation layer disposed on the IC, and an inductor disposed on the repassivation layer. The IC includes a gapped seal ring. The inductor may couple to an RFID tag antenna, thereby allowing the IC to transmit and receive RF signals.

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: Embodiments are directed to a Radio Frequency Identification (RFID) integrated circuit (IC) having a first circuit block electrically coupled to first and second antenna contacts. The first antenna contact is disposed on a first surface of the IC and the second antenna contact is disposed on a second surface of the IC different from the first surface. The first and second antenna contacts are electrically disconnected from each other.

Abstract: RFID tags, tag circuits, and methods are provided that reject at least in part the distortion caused to wireless signals by interference in the environment. When the received RF wave is converted into an unfiltered input (971), a filtered output (972) is generated that does not include an artifact feature deriving from the distortion. The filtered output is used instead of the unfiltered input, which results in tag operation as if there were less interference in the environment, or none at all.

Abstract: A Radio Frequency Identification (RFID) reader endorses an RFID tag by receiving an identifier from the tag; determining a certificate from the tag; challenging the tag with a challenge; receiving a response from the tag; sending a first message including at least the identifier, challenge, and response to a verification authority; sending a second message including at least the identifier and certificate to a certification authority; receiving a first reply from the verification authority; and receiving a second reply from the certification authority. The verification authority may notify a designated party if the response is incorrect or the certification authority may notify the designated party if the certificate is not supported.

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 integrated circuit (IC) includes a power rectifier component. The rectifier component includes a first current path formed by a first rectifying element, a second rectifying element, and a pump node coupled to the first and second rectifying elements. The first and second rectifying elements are coupled to a first phase of a radio frequency (RF) waveform while the pump node is coupled to a second phase of the RF waveform. The rectifier component also includes at least one biasing element coupled to the pump node and configured such that its terminal voltages vary with phases and amplitudes similar to that of the second phase of the RF waveform.

Abstract: A Radio Frequency Identification (RFID) system uses read difficulty factors (RDFs) to improve tag-parameter estimation. During inventory, a reader can obtain a tag's item identifier (II), determine a read metric such as a received signal strength indicator (RSSI), retrieve an RDF associated with the II, and adjust the RSSI using the RDF to more accurately estimate a tag parameter such as distance from the reader antenna. The system can then use the estimated distance to categorize the tag.

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: 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.

Abstract: RFID tag ICs employ tunneling-voltage profile calibration during IC manufacturing to determine and store, typically in nonvolatile memory, a tunneling-voltage profile for writing data to the IC's nonvolatile memory. The IC may subsequently read the profile at power-up, prior to writing the memory, or at other times as determined by the IC or by an interrogating reader, and may determine an actual ramp profile for writing to the nonvolatile memory based on the read profile and one or more operating conditions. By using the read profile to determine an actual ramp profile for writing to the nonvolatile memory, the IC may reduce nonvolatile memory write time and oxide stress.