Abstract: A method, system, and apparatus for remotely calibrating data symbols received by a radio frequency identification (RFID) tag population are described. Tags are interrogated by a reader, which may be located in a network of readers. The reader transmits data symbols to the tags. Tags respond to the interrogations with symbols that each represent one or more bits of data. To calibrate the tags, the reader transmits a plurality of pulses of different lengths to the tag population. The tags receive the plurality of pulses. A characteristic of each pulse, such as a pulse length, is stored by the tags. The stored pulse lengths are used to define different data symbols that are subsequently received by the tags from the reader.

Abstract: A system and method is provided for minimizing the unwanted re-negotiation of passive RFID tags. Each tag stores a confirmed read flag to indicate whether the tag has been previously read. During subsequent interrogations of the tag population, the reader has the capability to address all tags in a tag population or to address only unread tags. When addressing all tags, the reader sends a symbol causing all tags to ignore their confirmed read flag value. Each tag may also clear its confirmed read flag when this symbol is received. When addressing only unread tags, the reader sends a symbol causing each tag to evaluate its confirmed read flag value. Those tags that have a confirmed read flag value indicating “read” will enter dormant state and will not be re-negotiated. Those tags that have a confirmed read flag value indicating “not read” will continue to communicate with the reader.

Abstract: Methods and systems for the negotiation of a population of RFID tags with improved security is provided. In one aspect, a binary traversal is performed to singulate tags without using information that directly identifies the tags in the tag population. A key is generated to identify each RFID tag of the population of RFID tags. The generated key does not include bits identifying an item with which the particular RFID tag is associated. A binary tree algorithm is operated to identify one or more tags in the population of RFIDs tags using the generated keys. In another aspect, frequency hopping and/or spread spectrum techniques are used to provide improved security while negotiating tags. In another aspect, the reader causes the tags to scroll series of bits back to the reader for each bit sent to the tags to provide improved security.

Abstract: A system and method for conducting an inventory of tags, wherein each tag is assigned a Tag ID and a manufacturer number. Each tag can be attached to an item to take inventory of those items. A tag reader transmits a wake-up signal followed by at least one clock signal. Each tag increments a first tag count in response to the clock signals, and transmits the Tag ID assigned to the tag when the first tag count corresponds to the Tag ID assigned to the tag. The tag reader records the transmitted Tag IDs. When more than one tag transmits simultaneously, the tag stores the Tag ID in order to resolve the contention when the first read cycle is complete. In the second read cycle, the tag reader transmits the contended Tag ID followed by at least one clock signal.

Abstract: An identification (ID) tag includes a substrate having an input capable of receiving a high frequency signal. For instance, the high frequency signal can be a radio frequency (RF) signal that is generated as part of a radio frequency (RF) ID system. A first charge pump is coupled to the input and is configured to convert the high frequency signal to a substantially direct current (DC) voltage. A data recovery circuit is coupled to the input and is capable of recovering data from the high frequency signal. A back scatter switch is coupled to the input and is capable of modifying an impedance of the input, responsive to a control signal. A state machine is disposed on the substrate and is responsive to the data recovered by the second charge pump, where the state machine is capable of generating the control signal for the back scatter switch in response to the data.

Abstract: A method, system, and apparatus for a die frame, and for transferring integrated circuit dies therewith, is described. A ring shaped groove is formed in a first surface of a wafer around a plurality of dies. The wafer is scribed to form a grid of grooves in the first surface of the wafer that separates the plurality of dies. A solidifiable material is applied to the first surface of the wafer to substantially fill the ring shaped groove and the grooves of the grid. The solidifiable material is caused to harden into a ring shaped hardened material in the ring shaped groove and into a grid shaped hardened material in the grooves of the grid. The wafer is thinned so that the grid shaped hardened material removably holds the plurality of dies.

Abstract: An RFID tag that includes a die having one or more connecting pads is assembled. A plurality of dies separated die from a wafer are attached to a support surface. The plurality of dies is transferred from the support surface to a substrate structure that includes a plurality of tag substrates.

Abstract: A method and system for transferring a plurality of integrated circuit dies from a first surface to a second surface is described. The second surface is positioned to be closely adjacent to the first surface that has a plurality of dies attached thereto. A distance is reduced between the first surface and the second surface until the plurality of dies contact the second surface and attach to the second surface due to an adhesiveness of the second surface. The first surface and second surface are moved apart. The plurality of dies remain attached to the second surface.

Abstract: A method and system for transferring a plurality of integrated circuit dies from a first surface to a second surface is described. Each hollow barrel of a plurality of hollow barrels is applied to a respective die residing on the first surface. The respective die is caused to move into each hollow barrel in parallel. These steps are repeated until each hollow barrel contains a stack of dies of a predetermined number. A die from each hollow barrel is deposited onto the second surface until the stack of dies contained by each hollow barrel is substantially depleted.

Abstract: A method, system, and apparatus for a die frame, and for transferring integrated circuit dies therewith, is described. In one aspect for making a die frame, a wafer that comprises a plurality of dies is attached to a surface of a tape structure. A grid of grooves is formed in the wafer to separate the plurality of dies on the surface of the tape structure. A portion of the tape structure that is accessible through the grooves of the grid is caused to harden into a grid shaped structure. The grid shaped structure removably holds the plurality of dies. One or more dies of the plurality of dies can be moved from the grid shaped structure onto a target surface. In an alternative aspect, when the grid of grooves is formed in the wafer to separate the plurality of dies on the surface of the tape structure, the surface of the tape structure is breached in the grooves.

Abstract: A method and system for optimizing an interrogation of a tag population that includes a plurality of tags, wherein each of the plurality of tags is assigned a tag address includes determining a tag population size; selecting one of a plurality of efficiency profiles that matches the determined tag population size; and defining a plurality of interrogation read cycles according to the selected efficiency profile.

Abstract: A charge pump is configured to convert a high frequency signal to a substantially direct current (DC) voltage. The charge pump includes an input capable of receiving the high frequency signal, and a plurality of stages parallel connected to the charge pump input. Charge from the high frequency signal is accumulated in the plurality of stages during a first half cycle of the high frequency signal, and is passed from a nth stage of the plurality of stages to a (n+1)th stage of the plurality of stages during a second half cycle of said high frequency signal, the (n+1)th stage being closer to the charge pump output than the nth stage. The accumulated charge increases as it moves through the plurality of stages to the charge pump output to produce a DC output voltage that is sufficiently stable to be utilized as a power supply. In embodiments of the invention, the charge pump is configured on a radio frequency (RF) identification (ID) tag, and the DC voltage provides the power supply for the RF ID tag.

Abstract: A charge pump is configured to convert a high frequency signal to a substantially direct current (DC) voltage. The charge pump includes an input capable of receiving the high frequency signal, and a plurality of stages parallel connected to the charge pump input. Charge from the high frequency signal is accumulated in the plurality of stages during a first half cycle of the high frequency signal, and is passed from a nth stage of the plurality of stages to a (n+1)th stage of the plurality of stages during a second half cycle of said high frequency signal, the (n+1)th stage being closer to the charge pump output than the nth stage. The accumulated charge increases as it moves through the plurality of stages to the charge pump output to produce a DC output voltage that is sufficiently stable to be utilized as a power supply. In embodiments of the invention, the charge pump is configured on a radio frequency (RF) identification (ID) tag, and the DC voltage provides the power supply for the RF ID tag.

Abstract: A radio frequency identification (RFID) architecture is described. RFID tags are interrogated by a reader, which may be located in a network of readers. The reader transmits symbols to the tags. Tags respond to the interrogations with symbols that each represent one or more bits of data. An RFID tag includes an antenna pad, a receiver, a state machine, and a modulator. The receiver is coupled to the antenna pad. The receiver receives a symbol from the antenna pad and outputs a received signal. The state machine is configured to determine a response symbol from the received signal and an operating state of the tag. The modulator is coupled to the antenna pad. The modulator is configured to backscatter modulate the received symbol with the response symbol. The modulator is configured to output the backscatter modulated symbol to the antenna pad.

Abstract: A method, system, and apparatus for interrogating a radio frequency identification (RFID) tag population are described. Tags are interrogated by a reader. The reader and tags engage in communication according to binary traversal algorithms, where single bit data symbols are exchanged between the reader and tags. Furthermore, a reader implicitly controls the operating state of every tag in the tag population by transmitting a single data symbol. Bit patterns may be collected from the tags by the reader, using a variety of interrogation techniques. In a general interrogation, the reader exchanges symbols with the tag population to interrogate the entire tag population. In a specific interrogation, a reader exchanges symbols with the tag population to target a particular tag identification number. Tags may also be placed in a superposition state by the reader, where they respond whenever a received data symbol matches the next bit of their identification number.

Abstract: A method, system, and apparatus for communicating with a radio frequency identification (RFID) tag population that includes one or more tags are described. The tags are interrogated by a reader which may be located in a network of readers. The reader interrogates the tags by transmitting data symbols to the tags. Tags respond to the reader with backscatter symbols. Bit patterns, such as identification numbers stored in the tags, are collected from the plurality of tags without collisions. Collisions are avoided because the backscatter symbols transmitted by the tags use different characteristics to represent different data bits. For example, a first backscatter symbol frequency is used by the tag to represent a “0” bit, and a second backscatter symbol frequency is used by the tag to represent a “1” bit.

Abstract: An identification (ID) tag includes a substrate having an input capable of receiving a high frequency signal. For instance, the high frequency signal can be a radio frequency (RF) signal that is generated as part of a radio frequency (RF) ID system. A first charge pump is coupled to the input and is configured to convert the high frequency signal to a substantially direct current (DC) voltage. A data recovery circuit is coupled to the input and is capable of recovering data from the high frequency signal. A back scatter switch is coupled to the input and is capable of modifying an impedance of the input, responsive to a control signal. A state machine is disposed on the substrate and is responsive to the data recovered by the second charge pump, where the state machine is capable of generating the control signal for the back scatter switch in response to the data.

Abstract: A method, system, and apparatus for a timing subsystem in a radio frequency identification tag device are described. The timing subsystem provides a system oscillator or clock for the tag. The timing subsystem also provides frequencies used by an RF interface of the tag to generate backscatter modulated symbols. The timing subsystem also provides for oscillator calibration. The tag receives one or more oscillator calibration waveforms transmitted by a reader. The timing subsystem in the tag uses the oscillator calibration waveforms to successively adjust the frequency of the tag oscillator to a frequency desired by the reader. Hence, the reader may increase or decrease the oscillator frequency in the tag depending on the particular application. Furthermore, the reader may adjust the oscillator frequency for all tags in a population of tags using a single transmission of the one or more oscillator calibration waveforms.

Abstract: A method, system, and apparatus for remotely calibrating data symbols received by a radio frequency identification (RFID) tag population are described. Tags are interrogated by a reader, which may be located in a network of readers. The reader transmits data symbols to the tags. Tags respond to the interrogations with symbols that each represent one or more bits of data. To calibrate the tags, the reader transmits a plurality of pulses of different lengths to the tag population. The tags receive the plurality of pulses. A characteristic of each pulse, such as a pulse length, is stored by the tags. The stored pulse lengths are used to define different data symbols that are subsequently received by the tags from the reader.

Abstract: A charge pump is configured to convert a high frequency signal to a substantially direct current (DC) voltage. The charge pump includes an input capable of receiving the high frequency signal, and a plurality of stages parallel connected to the charge pump input. Charge from the high frequency signal is accumulated in the plurality of stages during a first half cycle of the high frequency signal, and is passed from a nth stage of the plurality of stages to a (n+1)th stage of the plurality of stages during a second half cycle of said high frequency signal, the (n+1)th stage being closer to the charge pump output than the nth stage. The accumulated charge increases as it moves through the plurality of stages to the charge pump output to produce a DC output voltage that is sufficiently stable to be utilized as a power supply. In embodiments of the invention, the charge pump is configured on a radio frequency (RF) identification (ID) tag, and the DC voltage provides the power supply for the RF ID tag.