Abstract: An RFID tag's mobility can be increased and cost can be decreased by using high-performance mobile power antennas instead of battery powered tags. Disclosed are some power antennas that include a half wave rectifier, a full wave rectifier, and a voltage multiplier. These antennas can be cascaded to boost the power or voltage gain. Additionally, planar elements can be added to increase efficiency without decreasing mobility.

Abstract: A Write Broadcast system and method uses a base station to write sent data to all or some selected number (sub group) of tags in a base station field simultaneously. By unselecting the tags that have been successfully written to, and requesting a response from the remaining tags in the field (or sub group), the system determines, by receiving a response to the request, that there are tags in the field (sub group) that were unsuccessfully written to. Another Write Broadcast signal is sent to these tags. The system is useful for quickly (simultaneously) “stamping” information on the tag memory of a large number of tags in the field of the base station.

Abstract: An RFID tag's mobility can be increased and cost can be decreased by using high-performance mobile power antennas instead of battery powered tags. Disclosed are some power antennas that include a half wave rectifier, a full wave rectifier, and a voltage multiplier. These antennas can be cascaded to boost the power or voltage gain. Additionally, planar elements can be added to increase efficiency without decreasing mobility.

Abstract: The present invention assures the integrity of state information retained by a Radio Frequency Transponder during a loss of power. During the regular operation of the Transponder power is provided to a voltage-storing device powering an information retention mechanism of the Transponder. After the loss and reestablishing of power to the Transponder but before the Transponder is restarted, the voltage-storing device is checked to determine whether sufficient power is present in the information retention mechanism to retain information without corruption. If sufficient power is present, a signal to indicate that fact is communicated to the Transponder and the stored information is restored. The Transponder is then restarted.

Abstract: A passive radio frequency transponder (RF tag) having a diode rectifier receiver circuit outside the tag power rectification circuit, the tag power rectification circuit supplying power to the electronics of the RF tag. An additional innovative low current circuit protect the signal capacitor from overvoltage produced by the signal diode. An innovative circuit also clips the signal and sharpens it. An innovative low current circuit is used as a comparator to sharpen the signal pulses.

Abstract: A multistage voltage multiplying circuit for single chip passive RF tags is provided, wherein the parasitic capacitance of the diodes of each stage of the voltage multiplying circuit is much less than the parasitic capacitance of the diodes of the preceding stage.

Abstract: A master entity is capable of broadcasting commands to slaves which move to another state when they satisfy a primitive condition specified in the command. By moving slaves among three sets, a desired subset of slaves can be isolated in one of the sets. This desired subset of slaves ten can be moved to one of the states that is unaffected by commands that cause the selection of other desirable subsets of slaves. In the incorporated U.S. Pat. Nos. 5,550,547 and 5,673,037, certain subgroups of radio frequency tags are selected for querying, communicating, and/or identifying by commands from a base station.

Abstract: An RFID tag is powered both by an internal battery and passively by an interrogating RF field. As a result, the RFID tag can be passively powered after the internal battery has been depleted. More particularly, an embodiment of the RFID tag includes electronic circuitry to provide RFID functionality, and an energy storage device coupled to the electronic circuitry to provide an operational voltage thereto. A battery is operatively coupled to the energy storage device to charge the energy storage device. A rectified RF power source derived from an interrogating RF field is also operatively coupled to the energy storage-device to charge the energy storage device. The rectified RF power source and the battery are electrically separated from each other. The energy storage device remains charged by the battery in the absence of the RF interrogating field while the battery has remaining capacity.

Abstract: A Write Broadcast system and method uses a base station to write sent data to all or some selected number (sub group) of tags in a base station field simultaneously. By unselecting the tags that have been successfully written to, and requesting a response from the remaining tags in the field (or sub group), the system determines, by receiving a response to the request, that there are tags in the field (sub group) that were unsuccessfully written to. Another Write Broadcast signal is sent to these tags. The system is useful for quickly (simultaneously) “stamping” information on the tag memory of a large number of tags in the field of the base station.

Abstract: A multistage voltage multiplying circuit for single chip passive RF tags is provided, wherein the parasitic capacitance of the diodes of each stage of the voltage multiplying circuit is much less than the parasitic capacitance of the diodes of the preceding stage.

Abstract: The present invention provides an RFID transponder that includes a state holding cell that maintains the present state of the RFID transponder during temporary losses of power. After power is restored to the RFID transponder, the state holding cell restores the present state to the RFID transponder so that transactions with an RFID interrogator can continue without having re-transmit redundant commands. The RFID transponder further comprises an RF front end adapted to receive an interrogating RF signal. An analog circuit is coupled to the RF front end and is adapted to recover analog signals from the received interrogating RF signal. The analog circuit provides state information defining a desired state of the RFID transponder corresponding to the analog signals. A digital state machine is coupled to the analog circuit and adapted to execute at least one command in accordance with the state information.

Abstract: A Write Broadcast system and method uses a base station to write sent data to all or some selected number (sub group) of tags in a base station field simultaneously. By unselecting the tags that have been successfully written to, and requesting a response from the remaining tags in the field (or sub group), the system determines, by receiving a response to the request, that there are tags in the field (sub group) that were unsuccessfully written to. Another Write Broadcast signal is sent to these tags. The system is useful for quickly (simultaneously) “stamping” information on the tag memory of a large number of tags in the field of the base station.

Abstract: A multistage voltage multiplying circuit for single chip passive RF tags is provided, wherein the parasitic capacitance of the diodes of each stage of the voltage multiplying circuit is much less than the parasitic capacitance of the diodes of the preceding stage.

Abstract: The present invention provides an RFID transponder that includes a state holding cell that maintains the present state of the RFID transponder during temporary losses of power. After power is restored to the RFID transponder, the state holding cell restores the present state to the RFID transponder so that transactions with an RFID interrogator can continue without having re-transmit redundant commands. The RFID transponder further comprises an RF front end adapted to receive an interrogating RF signal. An analog circuit is coupled to the RF front end and is adapted to recover analog signals from the received interrogating RF signal. The analog circuit provides state information defining a desired state of the RFID transponder corresponding to the analog signals. A digital state machine is coupled to the analog circuit and adapted to execute at least one command in accordance with the state information.

Abstract: A bandgap reference generator includes a bandgap reference circuit, a sensing circuit, and a current injector circuit. The bandgap reference circuit includes an input for receiving a supply voltage VCC and an output for providing a reference voltage VREF. The bandgap reference circuit also has a first internal node with a first voltage and a second internal node with a second voltage. The sensing circuit is operatively coupled to the bandgap reference circuit for sensing the second voltage at the second node. The current injection circuit is responsive to the sensing circuit for injecting bootstrap current into the first internal node until the second voltage reaches a threshold voltage. The current injection circuit is operative to inject the bootstrap current into the first internal node during an initial condition of the bandgap reference circuit to cause the bandgap reference circuit to quickly transition to a desired operating state.

Abstract: The present invention provides an RF tag having an antenna that can be selectively tuned to achieve optimal performance. The RF tag comprises an RF transponder integrated circuit and an antenna connected to the RF transponder integrated circuit. The antenna includes components such as tuning stubs and loading bars that are physically alterable to selectively vary the performance characteristics of the antenna. The tuning stub and loading bar may each further comprising a variably selectable length having elements that may be removed by punching, cutting, etching, laser trimming or other process. The antenna may further comprise a leadframe or a flexible substrate.

Abstract: An RFID tag is powered both by an internal battery and passively by an interrogating RF field. As a result, the RFID tag can be passively powered after the internal battery has been depleted. More particularly, an embodiment of the RFID tag includes electronic circuitry to provide RFID functionality, and an energy storage device coupled to the electronic circuitry to provide an operational voltage thereto. A battery is operatively coupled to the energy storage device to charge the energy storage device. A rectified RF power source derived from an interrogating RF field is also operatively coupled to the energy storage device to charge the energy storage device. The rectified RF power source and the battery are electrically separated from each other. The energy storage device remains charged by the battery in the absence of the RF interrogating field while the battery has remaining capacity.

Abstract: A bandgap reference generator includes a bandgap reference circuit, a sensing circuit, and a current injector circuit. The bandgap reference circuit includes an input for receiving a supply voltage VCC and an output for providing a reference voltage VREF. The bandgap reference circuit also has a first internal node with a first voltage and a second internal node with a second voltage. The sensing circuit is operatively coupled to the bandgap reference circuit for sensing the second voltage at the second node. The current injection circuit is responsive to the sensing circuit for injecting bootstrap current into the first internal node until the second voltage reaches a threshold voltage. The current injection circuit is operative to inject the bootstrap current into the first internal node during an initial condition of the bandgap reference circuit to cause the bandgap reference circuit to quickly transition to a desired operating state.

Abstract: A Write Broadcast system and method uses a base station to write sent data to all or some selected number (sub group) of tags in a base station field simultaneously. By unselecting the tags that have been successfully written to, and requesting a response from the remaining tags in the field (or sub group), the system determines, by receiving a response to the request, that there are tags in the field (sub group) that were unsuccessfully written to. Another Write Broadcast signal is sent to these tags. The system is useful for quickly (simultaneously) “stamping” information on the tag memory of a large number of tags in the field of the base station.

Abstract: An apparatus, method, and system are provided for sending radio frequency (RF) power to RF transponders (RFID tags), wherein the frequency sent to the tags is changed very rapidly.