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: 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. A substrate of the RFID IC, or a portion of the IC substrate, electrically couples the first circuit block to at least one of the first and second antenna contacts. The IC includes one or more interfaces or barrier regions that at least partially electrically isolate the first circuit block from the rest of the IC substrate.

Abstract: Embodiments are directed to mitigating power-based impedance changes in Radio Frequency Identification (RFID) tags. The intrinsic impedance of components in an RFID tag front-end may change as incident RF power on the tag changes, causing the input impedance of the front-end to change and altering the RF properties of the RFID tag. A number of approaches can be used to mitigate input impedance variations due to power variations. One approach involves adjusting the operating point of one or more components in the RFID tag front-end to change their intrinsic impedances so as to counteract or mitigate the RF-power-based input impedance variation.

Abstract: RFID ICs sense and indicate changes in their surrounding environment, such as changes in temperature, humidity, chemical presence, RF signals, and similar. An RFID IC indicates when a significant environmental change has occurred, for example by adjusting the value of a flag, writing data to memory, transmitting a message to an external entity, exiting a sleep state, and/or responding repeatedly to an inventorying reader. In some cases, RFID IC actively notifies an external entity that a significant environmental change has been sensed. For example, RFID IC may alert the external entity by participating in a special inventory process meant for RFID ICs sending environmental change. The RFID IC may alert the external entity by interjecting itself into an inventory round, re-participating in an inventory round, refraining from entering a sleep state after inventorying, and/or adjusting timing of a scheduled reply to communicate with an RFID reader ahead of schedule.

Abstract: RFID systems may be configured to use session-dependent replies. When an RFID tag is involved in a certain inventorying session, the tag may respond to inventorying commands with a reply that is at least partly generated based on the session. For example, the tag may generate a reply with a string that has parity based on the session or includes an identifier for the session. The string may be a random number, a tag identifier or item identifier, or any other suitable data sent from the tag.

Abstract: Techniques are provided to estimate the location of an RFID tag using tag read information, such as a tag read count or a tag read rate, and an opportunity metric, such as an inventory cycle duration, inventory cycle rate, or inventory cycle count. A tag tracking system determines read information for a tag in a zone and an opportunity metric associated with the tag and the zone. The tag tracking system then computes a success rate based on the tag read information and opportunity metric, and uses the success rate to estimate the location of the tag.

Abstract: RFID inlays or straps may be assembled using impulse heating of metal precursors. Metal precursors are applied to and/or included in contacts on an RFID IC and/or terminals on a substrate. During assembly of the tag, the IC is disposed onto the substrate such that the IC contacts physically contact either the substrate terminals or metal precursors that in turn physically contact the substrate terminals. Impulse heating is then used to rapidly apply heat to the metal precursors, processing them into metallic structures that electrically couple the IC contacts to the substrate terminals.

Abstract: RFID-tagged items can be filtered based on relevance estimation or user input. A device reads digital identifiers for multiple RFID-tagged items. The device estimates and selects an item that an individual desires based on one or more metrics, then presents data about the selected item to the individual. If the device receives feedback that the selected item is not the desired item, then the device may estimate and select another item and/or present information about multiple items to allow the individual to select the desired item. When the desired item is selected, the device may perform some associated action.

Abstract: A level shifter circuit configured to convert a digital input signal with a first high logic level to a digital output signal having a second high logic level substantially higher than the first high logic level is provided. The level shifter circuit may include a PMOS latch circuit configured to receive the digital input signal and having first and second latch outputs and a current mirror circuit having a mirror input and a mirror output. The mirror input may be at least partly gated by a switch having a control input. The mirror output may be coupled to the first latch output. The control input may be coupled to the first or second latch outputs, and the digital output signal is provided from the first and/or second latch outputs.

Abstract: RFID tags may compensate for non-RFID power sources by automatically enforcing data or state persistence even while powered. A tag may measure a time interval between successive detected modulated reader transmissions. If the interval exceeds a minimum time, then the tag may deassert a protocol flag, erase data, and/or change tag operating states, even if the tag would normally not perform these actions while powered.

Abstract: Embodiments are directed to restricting access to Radio Frequency Identification (RFID) tag information based on location. Access to RFID tag information may be restricted at the reader level, at the requester level, and at the network level. When reader-level restrictions exist, devices may be prevented from inventorying tags and retrieving information from tags. When requester-level restrictions exist, a requester or device may be prevented from receiving tag information from inventoried tags or a network. When network-level restrictions exist, a network may discard or otherwise restrict tag information received from devices.

Abstract: Messages may be passed between Radio Frequency Identification (RFID) tags using RFID readers. A first tag with a message intended for a second tag sends the message to an RFID reader. The reader then determines that the destination of the message is the second tag and sends the message to the second tag. The second tag may confirm receipt of the message by sending a receipt confirmation message to the reader for forwarding to the first tag, and/or the reader may itself confirm that the message was sent to the second tag by sending a transmit confirmation message to the first tag.

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: A Radio Frequency Identification (RFID) system including an RFID reader and a reader proxy authenticates itself to a verification authority. The proxy receives a proxy challenge from a verification authority and determines a proxy response based on the proxy challenge and a proxy key known to the proxy. The proxy response is then sent to the verification authority along with an identifier for the reader. The reader then authenticates an RFID tag by sending a tag response to the verification authority, which determines whether the reader is authentic based on the authenticity of the proxy response.

Abstract: Embodiments are directed to rectifiers using a single bias current or bias current path to bias multiple rectifying elements. A rectifier that has multiple rectifier stages coupled together serially includes a bias current path coupled to each of the rectifier stages. Thee bias current path is configured to simultaneously bias rectifying elements in each of the rectifier stages by using a bias current to bias a first rectifying element and reusing the bias current to bias other rectifying elements.

Abstract: RFID technology may be used to provide digital identities for physical items. An RFID IC attached to or integrated into a physical item contains an identifier for the physical item. Digital identity information associated with the item, such as ownership information, history, properties, and the like, may be located on one or more networks. An entity, after authenticating itself and/or the item, may use the identifier to locate, retrieve, and/or update the item's digital identity information on the network.

Abstract: RFID readers may be configured to supply power to tags during frequency hops. When a reader is supplying power to a passive RFID tag via a first RF waveform having a first radio frequency and determines that it is to frequency-hop, the reader may determine whether the tag requires power during the hop. If so, the reader begins (or continues) to synthesize a second RF waveform with a second radio frequency while also synthesizing the first RF waveform, and frequency-hops by transitioning from transmitting the first RF waveform to transmitting the second RF waveform such that the power transmitted during the transition is sufficient for the tag to operate.

Abstract: An authentication method includes RFID tags authenticating RFID readers. A tag sends a tag identifier and a reader challenge to a reader in response to one or more commands from the reader. The reader then either derives a response to the reader challenge itself or has a verification authority derive the response. The response may be derived from parameter(s) in the reader challenge, and may be derived using a cryptographic key. The reader then sends the response to the tag along with one or more commands. The tag verifies the response before executing action(s) associated with the command(s).

Abstract: An Integrated Circuit (IC) for an RFID tag includes at least two antenna ports for coupling to at least two antennas. The IC may be configured to determine the port from which it receives an input signal, and provide a first functionality if it receives the input from a first port and a second functionality if it receives the input from a second port. The IC may be configured to determine and/or offer a functionality based on the receiving port.