Abstract: Methods of and apparatuses for matching the signal delay, clock timing, frequency response, gain, offset, and/or transfer function of signal pathways in electrical circuits such as, for example, time-interleaved and pipelined circuits using analog-valued floating-gate MOSFETs are disclosed. The methods and apparatuses disclosed are applicable to a variety of circuits, including but not limited to, sample-and-hold or track-and-hold circuits, quadrature mixers, analog-to-digital converters (ADCs), digital-to-analog converters (DACs), analog or digital filters, and amplifiers.

Abstract: An interference canceller for a RFID reader senses a signal related to the interference signal in the receive path of the reader. The canceller outputs an adjustment signal that depends on the sensed signal, which is coupled into the receive path before a downconverter in the receive path. The canceller can use a signal derived from the transmit path in generating the adjustment signal. The canceller adjusts the amplitude or phase (or both) of the derived signal to form the adjustment signal so that it cancels a carrier feed-through interference signal when injected into the receive path. The canceller can include a vector modulator to adjust the amplitude and/or phase of the derived signal; or alternatively, the canceller can include a variable attenuator and a variable phase shifter to adjust the amplitude and/or phase of the derived signal. The loop can be continuous or non-continuous.

Abstract: An RFID tag that receives a calibration instruction from a reader can determine the basic backscatter period of the symbols to be backscattered. According to some embodiments, when the instruction includes a calibration feature that is to be divided by a divide ratio, the tag measures the duration of the feature in terms of numbers of internal pulses, resulting in a binary L-number. Then at least two versions of the L-number (PR1-number, PR2-number) are combined, so as to yield the effective result of the division alternately, even when the divide ratio is a non-integer. The backscatter period can then be determined from the BP-number and the period of the internal pulses.

Abstract: RFID system components, such as readers and tags, communicate where the reader inventories a population of tags. The reader evaluates responses from tags by categorizing them in slots. As tags are inventoried, the number of slots based on a Q-parameter is reduced. The reader reduces the Q-parameter first in a first manner, then in a second manner where the second manner is different from the first manner. The first manner and the second manner may be different algorithms, different subroutines of an algorithm, or the same damping algorithm with different damping parameters.

Abstract: RFID system components, such as readers and tags, communicate where the reader inventories a population of tags. The reader evaluates responses from tags by categorizing them in slots. As tags are inventoried, the number of slots based on a Q-parameter is reduced. The reader determines an interim value for the Q parameter, generates a Q1 value by applying the interim value to a damping function, and uses the Q1 value in another round of interrogation. The reader then determines whether to increase or decrease the interim value depending on the tag replies. The increase or decrease may be an increment or a decrement such as incrementing or decrementing a floating point number of the interim value in a damping function that is arranged to return an integer by rounding the floating point number.

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 system components, such as readers and tags, communicate where the reader inventories a population of tags. The tags choose randomly one of a plurality of slots in response to each one of the values communicated by the reader and reply according to their chosen slot. The reader may initiate the inventorying by determining a Q-parameter value from a stored value and communicating the Q-parameter value to the tags. The reader may evaluate replies received from the tags in another plurality of tags, determine a second value from evaluating the second replies, and store the second value for future use.

Abstract: An RFID reader inventories a population of tags. The reader evaluates responses from tags by categorizing them in slots. As tags are inventoried, the number of slots based on a Q-parameter is reduced. The reader addresses the tags by communicating a Q1 value for the Q parameter, generates first contents from replies received from the tags, and computes a first merit statistic based on the first contents. Then, the reader repeats the process with a Q2 value. Upon computing the first and the second merit statistics, the reader determines a Q3 value for the Q parameter. If the Q3 value is substantially equal to the Q1 value, the reader continues to receive the second replies without communicating the Q3 value. If the Q3 value is different from the Q2 value, the reader uses the Q3 value for another round of iteration heuristically converging on an optimum Q value.

Abstract: An RFID reader inventories a population of tags. The reader evaluates responses from tags by categorizing them in slots. As tags are inventoried, the number of slots based on a Q-parameter is reduced. The reader addresses the tags by communicating a Q1 value for the Q parameter, generates first contents from replies received from the tags, and computes a first merit statistic based on the first contents. Next, the reader determines a Q2 value for the Q parameter, which if used in the same way would meet a preset fairway condition better than the first merit statistic. After determining the Q2 value, the reader addresses a portion of the tags by communicating the Q2 value for the Q parameter.

Abstract: According to one aspect of the present invention, there is provided a method of calibrating an oscillator within a radio-frequency identification (RFID) circuit for use in an RFID tag. A plurality of calibration values is stored within a memory structure associated with the RFID circuit. Each of the calibration values corresponds to a respective oscillation frequency of the oscillator. A selected calibration value is selected from the plurality of calibration values stored within the memory structure, according to a first selection criterion. The oscillator is then calibrated in accordance with the selected calibration value.

Abstract: A process is disclosed for communicating with individual tags in a population of tags having a binary tree organization, wherein each tag corresponds to a leaf node of the binary tree. The process includes singulating a predetermined leaf node and returning to a designated re-entry node associated with the predetermined leaf node after singulating.

Abstract: In accordance with one aspect of the present invention, there is provided a method of calibrating an oscillator within a radio-frequency identification (RFID) circuit for use in an RFID tag. The oscillator has an oscillation frequency. A calibration value is stored within a non-volatile memory associated with the RFID circuit. The oscillator is calibrated in accordance with the calibration value. The storing of the calibration value includes recovering a reference frequency from a test signal supplied to the RFID circuit, calculating the calibration value to correspond to a difference between the recovered reference frequency and the oscillator frequency, and writing the calibration value to the non-volatile memory.

Abstract: Rewriteable electronic fuses include latches and/or logic gates coupled to one or more nonvolatile memory elements. The nonvolatile memory elements are configured to be programmed to memory values capable of causing associated electronic circuits to settle to predetermined states as power-up or reset signals are applied to the fuses. Although not required, the nonvolatile memory elements used in the rewriteable electronic fuses may comprise floating-gate transistors. An amount of charge stored on the floating gate of a given floating-gate transistor determines the memory value and, consequently, the state to which a fuse settles upon power-up or reset of the fuse.

Abstract: According to one aspect of the present invention, there is provided a method to backscatter modulate a first radio-frequency (RF) signal from a radio-frequency identification (RFID) tag. An oscillator calibration value is retrieved from a non-volatile memory associated with the RFID tag. An oscillation frequency signal is generated within the RFID tag, the generating of the oscillation signal being performed utilizing the oscillator calibration value. A command signal is generated within the RFID tag, the command signal being based on command data received at the RFID tag in a second radio-frequency signal from an RFID reader. The first radio-frequency signal is backscatter modulated in accordance with both the oscillation frequency signal and the command signal.

Abstract: According to one aspect of the present invention, there is provided a method of calibrating an oscillator within a radio-frequency identification (RFID) circuit for use in an RFID tag. A first calibration value is stored within a non-volatile memory associated with the RFID circuit. The oscillator is calibrated in accordance with the first calibration value. The storing of the first calibration value is performed responsive to receiving a calibration command and an associated update value at the RFID circuit.

Abstract: According to one aspect of the present invention, there is provided a method to generate a demodulator clock signal and a modulator clock signal within an RFID circuit for use within an RFID tag. The demodulator clock signal is generated from a radio-frequency signal received at the RFID tag. A modulator clock signal is generated utilizing a first calibration value, stored within a non-volatile memory associated with the RFID tag.

Abstract: Rewriteable electronic fuses include latches and/or logic gates coupled to one or more nonvolatile memory elements. The nonvolatile memory elements are configured to be programmed to memory values capable of causing associated electronic circuits to settle to predetermined states as power-up or reset signals are applied to the fuses. Although not required, the nonvolatile memory elements used in the rewriteable electronic fuses may comprise floating-gate transistors. An amount of charge stored on the floating gate of a given floating-gate transistor determines the memory value and, consequently, the state to which a fuse settles upon power-up or reset of the fuse.

Abstract: Rewriteable electronic fuses include latches and/or logic gates coupled to one or more nonvolatile memory elements. The nonvolatile memory elements are configured to be programmed to memory values capable of causing associated electronic circuits to settle to predetermined states as power-up or reset signals are applied to the fuses. Although not required, the nonvolatile memory elements used in the rewriteable electronic fuses may comprise floating-gate transistors. An amount of charge stored on the floating gate of a given floating-gate transistor determines the memory value and, consequently, the state to which a fuse settles upon power-up or reset of the fuse.

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: Analog-valued floating-gate transistors are used as trimmable circuit components for modifying and/or controlling the gain, phase, offset, frequency response, current consumption, and/or transfer function of signal pathways in parallel and/or serial processing circuits in radio frequency, analog, or mixed-signal integrated circuits.