Abstract: RFID tag circuits, tags, and methods are provided for receiving a partial-kill command. In response to receiving such a command, the tag circuit or tag becomes partially killed. This means that one or more but not all of its memory functions become disabled.

Abstract: RFID tags and chips for RFID tags are capable of replying using changed reply timing. In a number of embodiments, this timing change is achieved when a tag receives a custom timing command from an RFID reader. In some embodiments, the changed reply timing affects an amount of delay before a tag backscatters a reply.

Abstract: Rogue RFID readers are detected by listening to communication between rogue reader and a tag, capturing a time stamp and/or a channel associated with the communication, and checking the captured time stamp/channel to determine whether it is a result of a command from another legitimate reader. Audible or visible alerts may be issued, flags may be set, or messages transmitted to an administrator upon determining the operation of the rogue RFID reader. Based on the alert(s) affected tags or the rogue reader may be jammed or an effect of the illegal transmission by the rogue reader may be reversed or tags replaced.

Abstract: Embodiments of the invention describe a core circuit for a reference current generator circuit that biases a first transistor to source a first current and a second transistor parallel to the first transistor, biased to source a second current controlled by the first current. A third transistor is coupled parallel to the second transistor and sources a third current controlled by the first current. The third transistor has a different threshold voltage than a threshold voltage of the second transistor. A resistive component coupled to conduct the second current has a resistive voltage that is substantially equal to a voltage differential between the first transistor and the second transistor. The conducting current through the resistive component is substantially independent of temperature variations.

Abstract: RFID readers transmit data to query tags at one or more data rates. Before transmitting data, the RFID readers also transmit special preambles that inform of the data rate that will be used for transmitting the data. The preambles have a call aspect and a rate aspect. The rate aspect has a feature substantially determined from a rate selected for transmitting the data. The feature may encode the rate indirectly or explicitly. The call aspect may be implemented by call transitions that define a timing, whose duration is independent of the selected rate. The duration may be advantageously set according to an assumed state of the RFID tag bandwidth filter. Therefore an RFID tag may use the call aspect of the preamble to prepare itself for receiving data, and the rate aspect to determine its rate of transmission for setting its filter bandwidth accordingly.

Abstract: Embodiments of the invention describe a core circuit for a reference current generator circuit that biases a first transistor to source a first current and a second transistor parallel to the first transistor, biased to source a second current controlled by the first current. A third transistor is coupled parallel to the second transistor and sources a third current controlled by the first current. The third transistor has a different threshold voltage than a threshold voltage of the second transistor. A resistive component coupled to conduct the second current has a resistive voltage that is substantially equal to a voltage differential between the first transistor and the second transistor. The conducting current through the resistive component is substantially independent of temperature variations.

Abstract: RFID tag circuits, tags, and methods are provided for using alternative memory lock bits. A pointer in tag memory is configured to point to one or the other of the alternative lock bits associated with a section of the memory for performing a function in response to a reader command. Upon receiving the reader command, the tag first checks the pointer and performs the function based on which lock bit(s) is selected.

Abstract: RFID reader systems, readers, components, software and methods are provided for inventorying RFID tags. In some embodiments, a population of RFID tags begins being inventoried using a first set of communication parameters, and then continues using a second set of communication parameters. This way, some RFID tags can be inventoried faster, without missing tags that require a longer time to read.

Abstract: A precursor for a Radio Frequency Identification (RFID) tag includes a conductive lead frame with at least three segments, an RFID Integrated Circuit (IC) with at least two antenna terminals, and at least two jumpers. The RFID IC is mounted on at least one of the segments. The antenna terminals are electrically coupled to at least two of the segments, and the jumpers electrically couple the segments such that the coupled segments form a two-turn coil between the antenna terminals of the RFID IC.

Abstract: RFID reader systems, components, software and methods are provided for use premises that have RFID-tagged items. When a person comes onto an enclosure of the premises already carrying a personal tag, the incoming code of that personal tag is read. When later the person exits the enclosure, they could be transporting some of the items that have actionable codes. The actionable codes can be read, but the incoming code can be removed from them, before the actionable codes are acted upon, in Point-of-Sale or Electronic Article Surveillance systems.

Abstract: RFID tags have an on-chip antenna and an off-chip antenna. One of the antennas can become uncoupled if the proper signal is received, while the other antenna may still operate. The uncoupled antenna can be the larger one, for example the off-chip antenna. Then the tag can then be read only by the smaller antenna, which effectively reduces the range of the RFID tag, but without disabling it entirely.

Abstract: RFID readers, computers, and methods are provided for reporting on the authentication of one or more RFID tags associated with a proffered item, while requiring special permissions be cleared before reporting. In some embodiments, a question is input about whether a Declared Password (DP) is regarded as proper for an Item Identifier (II), both of which have been input from the tags. An answer is generated for the question from the reference database, and transmitted to the user. The answer does not reveal an Actual Code that is indeed regarded as proper, unless the user first demonstrates they already know it. Beyond the authentication of the tag, the answer can further indicate the legitimacy of the proffered item, for a supply chain, at a Customs Office, etc.

Abstract: A system and method for generating a rectified signal in a RFID tag. An alternating signal is received by the RFID tag, and a first phase of the alternating signal is coupled to a gate and to a first non-controlling terminal of a first switching transistor. The non-controlling terminal of the first switching transistor is one of a source and a drain of the first switching transistor. A first bias voltage is applied between the first non-controlling terminal and the gate of the first switching transistor and a rectified voltage is received between the first non-controlling terminal and a second non-controlling terminal of the first switching transistor.

Abstract: RFID readers, systems, and methods are provided for overcoming the effects of RF interference. While a system is communicating in a channel, RF interference is monitored. If it is low, then hopping to another channel is performed according to an ordinary decision. But if interference is high, then hopping out to another channel can be earlier than would be dictated by the ordinary decision under the same circumstances. The earlier hopping out can result in diminishing communication in channels with a lot of RF interference.

Abstract: RFID readers, systems, and methods are provided for overcoming the effects of RF interference. While a system is communicating in a channel, RF interference is monitored. If it is low, then the next channel to be hopped onto is chosen in an unbiased manner. But if interference is high, then the next channel to be hopped onto is chosen in a biased manner that disfavors at least one channel over another, in view of the detected interference. The choice of the next channel can thus result in diminishing communication in channels with a lot of RF interference.

Abstract: Methods and apparatuses prevent overtunneling in nonvolatile floating gate memory (NVM) cells. An individual cell includes a circuit with a transistor that has a floating gate that stores charge, and a capacitor structure for extracting charge from the gate, such as by tunneling. A counteracting circuit prevents extracting charge from the floating gate beyond a threshold, therefore preventing overtunneling or correcting for it. In one embodiment, the counteracting circuit supplies electrons to the floating gate, to compensate for tunneling beyond a point. In another embodiment, the counteracting circuit includes a switch, and a sensor to trigger the switch when the appropriate threshold is reached. The switch may be arranged in any number of suitable ways, such as to prevent a high voltage from being applied to the capacitor structure, or to prevent a power supply from being applied to a terminal of the transistor or to a well of the transistor.

Abstract: A system and method for generating a rectified signal in a RFID tag. An alternating signal is received by the RFID tag, and a first phase of the alternating signal is coupled to a gate and to a first non-controlling terminal of a first switching transistor. The non-controlling terminal of the first switching transistor is one of a source and a drain of the first switching transistor. A first bias voltage is applied between the first non-controlling terminal and the first gate of the first switching transistor and a rectified voltage is received between the first non-controlling terminal and a second non-controlling terminal of the first switching transistor.

Abstract: Hot-electron injection driven by hole impact ionization in the channel-to-drain junction of a p-channel MOSFET provides a new mechanism for writing a floating-gate memory. Various pFET floating-gate structures use a combination of this mechanism and electron tunneling to implement nonvolatile analog memory, nonvolatile digital memory, or on-line learning in silicon. The memory is nonvolatile because the devices use electrically isolated floating gates to store electronic charge. The devices enable on-line learning because the electron injection and tunneling mechanisms that write the memory can occur during normal device operation. The memory updates and learning are bidirectional because the injection and tunneling mechanisms add and remove electrons from the floating gate, respectively. Because the memory updates depend on both the stored memory and the pFETs terminal voltages, and because they are bidirectional, the devices can implement on-line learning functions.

Abstract: A circuit for an RFID tag has at least two RF ports for driving points of the antenna that may correspond to different RF polarizations. The RF ports may be driven by a common modulating signal, or by separate modulating signals. Further, the ports may be coupled and uncoupled together, responsive to a control signal. The control signal may be the same as one or both of the modulating signals.

Abstract: RFID readers transmit data to query RFID tags. Before transmitting the data, the RFID readers also transmit special preambles that inform of parameters of communication that are to be used. RFID tags decode the preamble, and adjust accordingly to optimize the communication. The preambles of the invention start with a delimiter that has a substantially constant duration regardless of the communication parameters that will be used, such as transmission data rate.