Patents by Inventor Robert Callaghan Taft
Robert Callaghan Taft has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Publication number: 20180254780Abstract: A circuit including an amplifier array including an amplifier stage with M amplifiers (M?2), connected to a resistor interpolator (interpolation order N?2) including an input row and at least a second row, each row comprising interpolation resistors connected in series at nodes. The input row including M driven nodes connected to a respective amplifier, and connected in parallel to the second row, with at least some first-row interpolation nodes connected to corresponding second-row interpolation nodes. The resistor interpolator comprising at least one multi-row interpolation cell, with: in the input row, a driven node coupled through first and second interpolation resistors to respective adjacent first and second interpolation nodes; and in the second row, third and fourth interpolation nodes coupled through third and fourth interpolation resistors to an intermediate fifth interpolation node; and with the first and second interpolation nodes connected respectively to the third and fourth interpolation nodes.Type: ApplicationFiled: March 4, 2018Publication date: September 6, 2018Inventors: Robert Callaghan Taft, Alexander Bodem
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Publication number: 20180254269Abstract: An electronic circuit includes an electronic device, an input/output terminal, and a protection device. The electronic device includes a signal terminal to receive an input signal. The input/output terminal is configured to receive the input signal from a source external to the electronic circuit. The protection device is coupled to the electronic device and to the input/output terminal. The protection device is configured to protect the electronic device from voltage of the input signal exceeding a threshold. The protection device includes a first semiconductor region, a first contact, and a second contact. The first contact connects the first semiconductor region to the input/output terminal. The second contact connects the first semiconductor region to the signal terminal of the electronic device.Type: ApplicationFiled: November 29, 2017Publication date: September 6, 2018Inventors: Robert Callaghan TAFT, Tobias HOEHN, Karim Thomas TAGHIZADEH KASCHANI
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Publication number: 20180253122Abstract: Clock generation for capturing a repetitive signal relative to a clock includes clock circuitry to provide a clock with active and inactive clock edges within a clock period, and signal capture circuitry to capture repetitive signal transitions at an active clock edge, based on pre-defined setup and hold times which determine a setup/hold window. Clock phase adjustment circuitry is configured to adjust clock phase so that the repetitive signal transitions occur within a signal capture window between setup/hold windows. Clock phase adjustment can be based on: aligning the clock inactive edges to the repetitive signal transitions; and/or averaging successive phase comparisons of the clock and the repetitive signal transitions; and/or selectively performing an initial polarity inversion to generate a polarity inverted clock, and then adjusting clock phase of the polarity inverted clock. An example implementation is JESD204B (subclass1) to adjust DEVCLK phase relative to a SYSREF timing reference control signal.Type: ApplicationFiled: March 4, 2018Publication date: September 6, 2018Inventors: Paul Joseph Kramer, Matthew Hansen Childs, Robert Callaghan Taft
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Patent number: 7948423Abstract: A system, apparatus and method for continuous synchronization of multiple ADC circuits is described. The ADC circuits can be arranged in a master-slave configuration within the system so that the converter clock is subdivided into slower speeds for the data output clock or for the control of de-multiplexing the outputs onto a wider bus, while maintaining ADC-to-ADC synchronization resilient to perturbations from noise and other upset sources. The configuration of the ADCs in the master-slave configuration can be varied according to overall system requirements in any one of a sequential configuration, a parallel configuration or a tree type of configuration, as well as others. Digital and/or analog timing adjustments can be made to each of the ADC circuits. The master clocking signals can be generated by a master clock generator circuit, which is either internally implemented in an ADC circuit, or externally implemented as a separate master clock generator circuit.Type: GrantFiled: April 15, 2010Date of Patent: May 24, 2011Assignee: National Semiconductor CorporationInventors: Robert Callaghan Taft, Heinz Werker, Pier Francese, David Brian Barkin
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Patent number: 7920084Abstract: A system, apparatus and method for a folding analog-to-digital converter (ADC) are described. The general architecture of the folding ADC includes an array (1-N) of cascaded folding amplifier stages, a distributed array of fine comparators, and an encoder. Each folding amplifier stage includes folding amplifiers that are configured to receive inputs from a prior stage, and also generate output signals for the next stage. The folding amplifiers output signals for a given stage are evaluated by a corresponding comparator stage, which may include multiple comparators, and also optionally coupled to an interpolator. The outputs of the comparators from all stages are collectively evaluated by the encoder, which generates the output of the folding ADC. Unlike conventional folding ADCs that require fine and coarse channels, the presently described folding ADC provides conversion without the need for a coarse channel. The encoder can also be arranged to facilitate recursive error correction.Type: GrantFiled: March 3, 2010Date of Patent: April 5, 2011Assignee: National Semiconductor CorporationInventor: Robert Callaghan Taft
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Publication number: 20100201559Abstract: A system, apparatus and method for continuous synchronization of multiple ADC circuits is described. The ADC circuits can be arranged in a master-slave configuration within the system so that the converter clock is subdivided into slower speeds for the data output clock or for the control of de-multiplexing the outputs onto a wider bus, while maintaining ADC-to-ADC synchronization resilient to perturbations from noise and other upset sources. The configuration of the ADCs in the master-slave configuration can be varied according to overall system requirements in any one of a sequential configuration, a parallel configuration or a tree type of configuration, as well as others. Digital and/or analog timing adjustments can be made to each of the ADC circuits. The master clocking signals can be generated by a master clock generator circuit, which is either internally implemented in an ADC circuit, or externally implemented as a separate master clock generator circuit.Type: ApplicationFiled: April 15, 2010Publication date: August 12, 2010Inventors: Robert Callaghan Taft, Heinz Werker, Pier Francese, David Brian Barkin
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Publication number: 20100156691Abstract: A system, apparatus and method for a folding analog-to-digital converter (ADC) are described. The general architecture of the folding ADC includes an array (1-N) of cascaded folding amplifier stages, a distributed array of fine comparators, and an encoder. Each folding amplifier stage includes folding amplifiers that are configured to receive inputs from a prior stage, and also generate output signals for the next stage. The folding amplifiers output signals for a given stage are evaluated by a corresponding comparator stage, which may include multiple comparators, and also optionally coupled to an interpolator. The outputs of the comparators from all stages are collectively evaluated by the encoder, which generates the output of the folding ADC. Unlike conventional folding ADCs that require fine and coarse channels, the presently described folding ADC provides conversion without the need for a coarse channel. The encoder can also be arranged to facilitate recursive error correction.Type: ApplicationFiled: March 3, 2010Publication date: June 24, 2010Inventor: Robert Callaghan Taft
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Patent number: 7728753Abstract: A system, apparatus and method for continuous synchronization of multiple ADC circuits is described. The ADC circuits can be arranged in a master-slave configuration within the system so that the converter clock is subdivided into slower speeds for the data output clock or for the control of de-multiplexing the outputs onto a wider bus, while maintaining ADC-to-ADC synchronization resilient to perturbations from noise and other upset sources. The configuration of the ADCs in the master-slave configuration can be varied according to overall system requirements in any one of a sequential configuration, a parallel configuration or a tree type of configuration, as well as others. Digital and/or analog timing adjustments can be made to each of the ADC circuits. The master clocking signals can be generated by a master clock generator circuit, which is either internally implemented in an ADC circuit, or externally implemented as a separate master clock generator circuit.Type: GrantFiled: October 13, 2008Date of Patent: June 1, 2010Assignee: National Semiconductor CorporationInventors: Robert Callaghan Taft, Heinz Werker, Pier Francese, David Barkin
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Patent number: 7710305Abstract: A system, apparatus and method for a folding analog-to-digital converter (ADC) are described. The general architecture of the folding ADC includes an array (1-N) of cascaded folding amplifier stages, a distributed array of fine comparators, and an encoder. Each folding amplifier stage includes folding amplifiers that are configured to receive inputs from a prior stage, and also generate output signals for the next stage. The folding amplifiers output signals for a given stage are evaluated by a corresponding comparator stage, which may include multiple comparators, and also optionally coupled to an interpolator. The outputs of the comparators from all stages are collectively evaluated by the encoder, which generates the output of the folding ADC. Unlike conventional folding ADCs that require fine and coarse channels, the presently described folding ADC provides conversion without the need for a coarse channel. The encoder can also be arranged to facilitate recursive error correction.Type: GrantFiled: September 22, 2008Date of Patent: May 4, 2010Assignee: National Semiconductor CorporationInventor: Robert Callaghan Taft
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Publication number: 20100090876Abstract: A system, apparatus and method for continuous synchronization of multiple ADC circuits is described. The ADC circuits can be arranged in a master-slave configuration within the system so that the converter clock is subdivided into slower speeds for the data output clock or for the control of de-multiplexing the outputs onto a wider bus, while maintaining ADC-to-ADC synchronization resilient to perturbations from noise and other upset sources. The configuration of the ADCs in the master-slave configuration can be varied according to overall system requirements in any one of a sequential configuration, a parallel configuration or a tree type of configuration, as well as others. Digital and/or analog timing adjustments can be made to each of the ADC circuits. The master clocking signals can be generated by a master clock generator circuit, which is either internally implemented in an ADC circuit, or externally implemented as a separate master clock generator circuit.Type: ApplicationFiled: October 13, 2008Publication date: April 15, 2010Applicant: National Semiconductor CorporationInventors: Robert Callaghan Taft, Heinz Werker, Pier Francese, David Brian Barkin
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Publication number: 20100073215Abstract: A system, apparatus and method for a folding analog-to-digital converter (ADC) are described. The general architecture of the folding ADC includes an array (1?N) of cascaded folding amplifier stages, a distributed array of fine comparators, and an encoder. Each folding amplifier stage includes folding amplifiers that are configured to receive inputs from a prior stage, and also generate output signals for the next stage. The folding amplifiers output signals for a given stage are evaluated by a corresponding comparator stage, which may include multiple comparators, and also optionally coupled to an interpolator. The outputs of the comparators from all stages are collectively evaluated by the encoder, which generates the output of the folding ADC. Unlike conventional folding ADCs that require fine and coarse channels, the presently described folding ADC provides conversion without the need for a coarse channel. The encoder can also be arranged to facilitate recursive error correction.Type: ApplicationFiled: September 22, 2008Publication date: March 25, 2010Applicant: National Semiconductor CorporationInventor: Robert Callaghan Taft
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Patent number: 7525358Abstract: A clock receiver for an integrated circuit includes duty-cycle correction capabilities based on monitoring an average value associated with an internally generated clock signal. An active adjustment circuit within the clock receiver provides correction to each leg of the differential clock signal based on two correction signals. The correction signals are derived from a comparison of the average value associated with the internal clock signal with a target voltage. The target voltage is based on a trip-point of an inverter stage in a logic stage that is driven by the internal clock signal. The closed loop control of the correction signals adjusts the average value of the internal clock signal until it is substantially equal to the target voltage. By straddling the internal clock signal about the trip-point of the inverter stage, the duty-cycle associated with the internal clock signal is adjusted to substantially a 50% duty cycle.Type: GrantFiled: June 17, 2005Date of Patent: April 28, 2009Assignee: National Semiconductor CorporationInventors: Robert Callaghan Taft, Christopher Alan Menkus
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Patent number: 7436203Abstract: An integrated circuit requires on-chip termination resistor for minimizing reflections from input signals supplied by an external signal source. The input signal is applied across two bonding pads which serve as input terminals for the integrated circuit. The first bonding pad is coupled to a first on-chip terminating resistor through a first on-chip inductor. The second bonding pad is coupled to a second on-chip terminating resistor though a second on-chip inductor. The two on-chip inductors are arranged in a transformer configuration where the mutual inductance relative to the applied input signal is negative. During operation, the on-chip transformer arrangement effectively shorts common-mode signals to the on-chip terminating resistors and effectively blocks differential-mode signals from the on-chip terminating resistors. Effective bandwidth and common-mode rejection performance is improved with the described on-chip transformer arrangement.Type: GrantFiled: April 18, 2007Date of Patent: October 14, 2008Assignee: National Semiconductor CorporationInventors: Ols Hidri, Robert Callaghan Taft
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Patent number: 7332904Abstract: An on-chip resistor is calibrated with a sense circuit that compares a resistance associated with an off-chip resistor to the on-chip resistor via a current-mirror circuit and a comparator. A digital counter circuit evaluates the comparison and adjusts its count such that a variable digital control signal is provided to the on-chip resistor circuit. During the calibration of the on-chip resistor circuit, the resistance of the on-chip resistor can be matched to the resistance of the off-chip resistor according to a scaling factor (e.g., 1×, 2×, 2.5×, 10×, etc.) as may be desired. Once the resistance associated with the on-chip resistor circuit is sufficiently adjusted, another on-chip resistor (e.g., a terminating resistor of another circuit) can be adjusted from the counter value. Various other circuits can be disabled during the calibration of the on-chip resistor such that additional sources of error (e.g., supply variation, ground bounce, noise, etc.) are minimized.Type: GrantFiled: January 28, 2005Date of Patent: February 19, 2008Assignee: National Semiconductor CorporationInventors: Christopher Alan Menkus, Robert Callaghan Taft
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Patent number: 7236115Abstract: A circuit for reducing the maximum magnitude of the total current on each of a plurality of buses for an amplifier stage in a folding analog to digital converter. Each amplifier stage bus couples multiple transconductance circuits to a load. Also, each of the transconductance circuits is configured to output a separate transconductance current to its respective bus. Separate current source circuits are configured to provide a separate source current locally at the output of each of the transconductance circuits such that substantially less than the full amount of each transconductance current reaches the respective bus.Type: GrantFiled: January 22, 2004Date of Patent: June 26, 2007Assignee: National Semiconductor CorporationInventors: Christopher A. Menkus, Robert Callaghan Taft
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Patent number: 7136000Abstract: A track/hold circuit with an offset adjustment that can be used to compensate for offset errors from other parts of the system containing the track/hold circuit. The offset adjustment may be provided by impressing a voltage at an electrode of a capacitor of the track/hold circuit during a hold mode and not impressing the voltage at the capacitor electrode during the track mode. The offset adjustment signal may be generated using an adjustable current source to propagate a current through a resistance that is coupled to the track/hold circuit output node via a capacitor of a voltage capacitive divider circuit during the hold mode. The offset introduced into the track/hold mode output signal can be independent of the voltage stored in the voltage capacitive divider circuit just prior to adding the offset adjustment signal.Type: GrantFiled: June 17, 2005Date of Patent: November 14, 2006Assignee: National Semiconductor CorporationInventors: Ols Hidri, Robert Callaghan Taft
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Patent number: 7068194Abstract: Multiple switching circuits and current source circuits are arranged to operate as part of a compact unary DAC cell. The compact unary DAC cell can be combined with additional compact unary DAC cells to provide a scalable unary DAC system that may be segmented, non-segmented, single-ended, differential, or some other DAC topology that may employ one or more unary DAC cells. Each unary DAC cell is preferably comprised of transistors of a single type such that the maximum circuit density can be achieved. The current source circuits may each have equal current magnitudes. The total output current from the unary DAC cell corresponds to the combined currents from each of the current sources that are enabled.Type: GrantFiled: March 21, 2005Date of Patent: June 27, 2006Assignee: National Semiconductor CorporationInventor: Robert Callaghan Taft
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Patent number: 7064599Abstract: A signal transmission gate includes a switch such as a transistor. The switch includes a gate terminal adapted to receive a control voltage, and a source terminal and a drain terminal. One of the source and drain terminals is adapted to receive an input signal, and the output signal is provided on the other terminal. A constant-voltage boosting circuit generates the control voltage such that it has a substantially constant value above a voltage of the input signal. In one embodiment, the constant-voltage boosting circuit is coupled between the gate terminal and the terminal that receives the input voltage, and generates a substantially constant voltage difference. In one implementation, a component is employed that exhibits a characteristic voltage behavior, such as a diode, for generating the substantially constant voltage difference.Type: GrantFiled: November 19, 2003Date of Patent: June 20, 2006Assignee: National Semiconductor CorporationInventors: Robert Callaghan Taft, Maria Rosaria Tursi
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Patent number: 6590518Abstract: An electronic circuit that converts an analog input to a digital signal includes a series “string” of resistors that provides reference signals with ascending values across the string. The reference signals are organized in banks of reference signals, with each adjacent set sharing a major code boundary. A coarse bank of comparators compare the analog input to the major code boundary reference signals and provide a coarse logic output. Each bank of reference signals has a corresponding bank of switches, with each switch associated with a particular reference signal in the bank. All of the switches in a particular bank are closed or opened in unison when selected. A particular bank is selected based on the coarse logic output signal. The reference values corresponding to the selected bank are coupled to a fine bank of comparators, each fine bank comparator comparing the analog input signal to one of the selected reference values.Type: GrantFiled: April 3, 2001Date of Patent: July 8, 2003Assignee: National Semiconductor CorporationInventor: Robert Callaghan Taft
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Patent number: 6407596Abstract: An electronic circuit generates additional clock edges from a reference clock signal utilizing switch-capacitor techniques. The electronic circuit includes a first capacitance circuit and a second capacitance circuit separated by a switch. During a first time period, the switch is open and the first capacitance circuit is charged. During a second time period, the switch is closed and at least a portion of the charge stored in the first capacitance circuit is transferred to the second capacitance circuit. The amount of charge transferred depends upon the relative sizes of the capacitance circuits. During another time period, the second capacitance circuit is discharged until its associated potential reaches a threshold level corresponding to a threshold set by a level detector. Upon reaching the threshold level, the level detector outputs a logic signal. A high frequency clock signal is produced by combining the logic signal with the reference clock signal.Type: GrantFiled: April 3, 2001Date of Patent: June 18, 2002Assignee: National Semiconductor CorporationInventors: Robert Callaghan Taft, Chris William Papalias