Patents by Inventor William W. Walker

William W. Walker 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).

  • Patent number: 9355207
    Abstract: A method may include obtaining gate-level circuit design data that describes a gate-level circuit design. The gate-level circuit design data may include one or more instances of each of multiple cells that each may be associated with a corresponding default cell static timing data and a corresponding default cell stress data. The method may include selecting one of the instances of one of the multiple cells, determining in-design stress data associated with the selected instance, and determining whether the in-design stress data is not within a tolerance of the default cell stress data. In response to the in-design stress data not being within the tolerance of the default cell stress data, the method may include generating in-design static timing data describing a timing performance for the selected instance and updating the gate-level circuit design data such that the selected instance is associated with the in-design static timing data.
    Type: Grant
    Filed: June 4, 2014
    Date of Patent: May 31, 2016
    Assignee: FUJITSU LIMITED
    Inventor: William W. Walker
  • Patent number: 9348358
    Abstract: A clock multiplication and distribution system includes a first phase-lock-loop circuit, a second phase-lock-loop circuit, and a clock distribution network that electrically couples the first phase-lock-loop circuit and the second phase-lock-loop circuit. The first phase-lock-loop circuit may include a first feedback loop that includes a first integer divider circuit and may be configured to generate a first clock using a reference clock. A frequency of the first clock may be greater than a frequency of the reference clock. The second phase-lock-loop circuit may include a second feedback loop that includes a second integer divider circuit and may be configured to generate a second clock using the first clock. A frequency of the second clock may be greater than the frequency of the first clock.
    Type: Grant
    Filed: April 18, 2014
    Date of Patent: May 24, 2016
    Assignee: FUJITSU LIMITED
    Inventors: William W. Walker, Pradip Thachile, Nikola Nedovic
  • Patent number: 9270289
    Abstract: A system for signal generation may include a phase-locked-loop including a first oscillator. The system may also include a second oscillator. The first oscillator may be configured to generate a first signal based on a phase-locked-loop control signal generated by the phase-locked-loop. The second oscillator may be configured to generate a second signal based on the phase-locked-loop control signal such that a free-running frequency of the first signal is approximately equal to a free-running frequency of the second signal to obtain injection locking between the first oscillator and the second oscillator when energy from the first oscillator is coupled into the second oscillator.
    Type: Grant
    Filed: February 13, 2014
    Date of Patent: February 23, 2016
    Assignee: FUJITSU LIMITED
    Inventors: William W. Walker, Nikola Nedovic
  • Patent number: 9236853
    Abstract: A digital duty-cycle correction circuit may include an adjustment unit that may be configured to adjust a duty cycle of an oscillating signal based on an adjust signal to generate an adjusted oscillating signal and a sampling unit that may be configured to sample the adjusted oscillating signal. The circuit may also include a counting unit that may be configured to generate an indication of a number of samples of the adjusted oscillating signal that are at the low and high level and to adjust the indication using a selectable duty cycle modify signal based on a desired duty cycle of the adjusting oscillating signal. The circuit may also include a comparing and filtering unit that may be configured to generate the adjust signal based on a comparison of the indication with a comparison count. The indication may be adjustable such that the oscillating signal's duty cycle is adjustable.
    Type: Grant
    Filed: February 4, 2014
    Date of Patent: January 12, 2016
    Assignee: FUJITSU LIMITED
    Inventor: William W. Walker
  • Publication number: 20150356227
    Abstract: A method may include obtaining gate-level circuit design data that describes a gate-level circuit design. The gate-level circuit design data may include one or more instances of each of multiple cells that each may be associated with a corresponding default cell static timing data and a corresponding default cell stress data. The method may include selecting one of the instances of one of the multiple cells, determining in-design stress data associated with the selected instance, and determining whether the in-design stress data is not within a tolerance of the default cell stress data. In response to the in-design stress data not being within the tolerance of the default cell stress data, the method may include generating in-design static timing data describing a timing performance for the selected instance and updating the gate-level circuit design data such that the selected instance is associated with the in-design static timing data.
    Type: Application
    Filed: June 4, 2014
    Publication date: December 10, 2015
    Inventor: William W. WALKER
  • Publication number: 20150301557
    Abstract: A clock multiplication and distribution system includes a first phase-lock-loop circuit, a second phase-lock-loop circuit, and a clock distribution network that electrically couples the first phase-lock-loop circuit and the second phase-lock-loop circuit. The first phase-lock-loop circuit may include a first feedback loop that includes a first integer divider circuit and may be configured to generate a first clock using a reference clock. A frequency of the first clock may be greater than a frequency of the reference clock. The second phase-lock-loop circuit may include a second feedback loop that includes a second integer divider circuit and may be configured to generate a second clock using the first clock. A frequency of the second clock may be greater than the frequency of the first clock.
    Type: Application
    Filed: April 18, 2014
    Publication date: October 22, 2015
    Applicant: FUJITSU LIMITED
    Inventors: William W. WALKER, Pradip THACHILE, Nikola NEDOVIC
  • Publication number: 20150240824
    Abstract: A ceiling fan hanging system (10) in disclosed which includes a motor (12), a downrod coupler (13), a hollow downrod (15), and a canopy assembly (16). The downrod includes an elongated shaft (22) defined by a cylindrical sidewall (23) having window or access port (24) therein. An access panel (27) is removably mounted to the downrod shaft. The fan electrical wires or leads (34) extend from the motor upwardly through the downrod coupler and into the bottom end of the downrod. The electrical wire leads are spliced to the bottom end of a length of extension electrical wires (36) at the location of the window. The extension electrical wires extend upwardly through the interior of the downrod (15) and are coupled to the structure or building electrical wires at the canopy assembly.
    Type: Application
    Filed: February 21, 2014
    Publication date: August 27, 2015
    Applicant: Hunter Fan Company
    Inventors: Rickey T. Jones, William W. Walker, JR.
  • Publication number: 20150229316
    Abstract: A system for signal generation may include a phase-locked-loop including a first oscillator. The system may also include a second oscillator. The first oscillator may be configured to generate a first signal based on a phase-locked-loop control signal generated by the phase-locked-loop. The second oscillator may be configured to generate a second signal based on the phase-locked-loop control signal such that a free-running frequency of the first signal is approximately equal to a free-running frequency of the second signal to obtain injection locking between the first oscillator and the second oscillator when energy from the first oscillator is coupled into the second oscillator.
    Type: Application
    Filed: February 13, 2014
    Publication date: August 13, 2015
    Applicant: FUJITSU LIMITED
    Inventors: William W. WALKER, Nikola NEDOVIC
  • Publication number: 20150222254
    Abstract: A digital duty-cycle correction circuit may include an adjustment unit that may be configured to adjust a duty cycle of an oscillating signal based on an adjust signal to generate an adjusted oscillating signal and a sampling unit that may be configured to sample the adjusted oscillating signal. The circuit may also include a counting unit that may be configured to generate an indication of a number of samples of the adjusted oscillating signal that are at the low and high level and to adjust the indication using a selectable duty cycle modify signal based on a desired duty cycle of the adjusting oscillating signal. The circuit may also include a comparing and filtering unit that may be configured to generate the adjust signal based on a comparison of the indication with a comparison count. The indication may be adjustable such that the oscillating signal's duty cycle is adjustable.
    Type: Application
    Filed: February 4, 2014
    Publication date: August 6, 2015
    Applicant: FUJITSU LIMITED
    Inventor: William W. WALKER
  • Patent number: 8903698
    Abstract: A system for generating behavioral models for analog circuits may include a database that is configured to store a parameterized hardware description language model of an analog circuit and an analog circuit simulator template of the analog circuit. The system may also include an interface module configured to receive data for an instance of the analog circuit in a schematic format. The system may also include an analog circuit simulator configured to use the received data and the analog circuit simulator template to generate a value for a parameter of the parameterized hardware description language model of the analog circuit. The system may also include a model constructor configured to generate a behavioral hardware description language model of the instance of the analog circuit based on the parameterized hardware description language model of the analog circuit and the generated value.
    Type: Grant
    Filed: May 15, 2012
    Date of Patent: December 2, 2014
    Assignee: Fujitsu Limited
    Inventor: William W. Walker
  • Patent number: 8718217
    Abstract: In one embodiment, a circuit includes a voltage-controlled oscillator (VCO) configured to generate k first clock signals that each have a first phase based on a charge-pump control voltage signal; one or more phase interpolators (PIs) configured to receive the k first clock signals and one or more first feedback controls signals and generate m second clock signals that each have a second phase based on the k first clock signals and the one or more first feedback control signals; a first phase detector (PD) configured to receive the m second clock signals and generate the one or more first feedback control signals based on the m second clock signals; a second PD configured to generate one or more second feedback control signals based on the m second clock signals; and a charge pump configured to output the charge-pump control voltage signal based on the second feedback control signals.
    Type: Grant
    Filed: July 29, 2009
    Date of Patent: May 6, 2014
    Assignee: Fujitsu Limited
    Inventors: William W. Walker, H. Anders Kristensson, Nikola Nedovic, Nestor Tzartzanis
  • Patent number: 8659973
    Abstract: In one embodiment, a method includes, in response to assertion of a write-enable signal at a memory array that comprises a plurality of words, sequentially and at a first clock frequency writing data to the memory array starting at a beginning of the memory array until the memory array is full. The method includes, independent of the writing of data to the memory array, asynchronously and at a second clock frequency that is slower than the first clock frequency reading data from the memory array based on read addresses received at the memory array.
    Type: Grant
    Filed: June 18, 2010
    Date of Patent: February 25, 2014
    Assignee: Fujitsu Limited
    Inventors: Scott McLeod, William W. Walker
  • Publication number: 20140015569
    Abstract: A frequency synthesizer circuit includes a phase determinator configured to output a phase difference signal based on a phase difference between an output signal and a reference signal. The frequency synthesizer circuit may further include a voltage controlled oscillator configured, during a fine tuning mode, to generate the output signal based on the phase difference signal and a value of a frequency band signal. The voltage controlled oscillator may be further configured, during a coarse tuning mode, to generate the output signal based on a voltage and the value of the frequency band signal. The frequency synthesizer circuit may further include a control unit configured to generate the frequency band signal. The value of the frequency band signal may be static during the fine tuning mode and changing during the coarse tuning mode based on a frequency difference between the reference signal and the output signal.
    Type: Application
    Filed: July 11, 2012
    Publication date: January 16, 2014
    Applicant: FUJITSU LIMITED
    Inventor: William W. WALKER
  • Patent number: 8618840
    Abstract: A frequency synthesizer circuit includes a phase determinator configured to output a phase difference signal based on a phase difference between an output signal and a reference signal. The frequency synthesizer circuit may further include a voltage controlled oscillator configured, during a fine tuning mode, to generate the output signal based on the phase difference signal and a value of a frequency band signal. The voltage controlled oscillator may be further configured, during a coarse tuning mode, to generate the output signal based on a voltage and the value of the frequency band signal. The frequency synthesizer circuit may further include a control unit configured to generate the frequency band signal. The value of the frequency band signal may be static during the fine tuning mode and changing during the coarse tuning mode based on a frequency difference between the reference signal and the output signal.
    Type: Grant
    Filed: July 11, 2012
    Date of Patent: December 31, 2013
    Assignee: Fujitsu Limited
    Inventor: William W. Walker
  • Publication number: 20130311152
    Abstract: A system for generating behavioral models for analog circuits may include a database that is configured to store a parameterized hardware description language model of an analog circuit and an analog circuit simulator template of the analog circuit. The system may also include an interface module configured to receive data for an instance of the analog circuit in a schematic format. The system may also include an analog circuit simulator configured to use the received data and the analog circuit simulator template to generate a value for a parameter of the parameterized hardware description language model of the analog circuit. The system may also include a model constructor configured to generate a behavioral hardware description language model of the instance of the analog circuit based on the parameterized hardware description language model of the analog circuit and the generated value.
    Type: Application
    Filed: May 15, 2012
    Publication date: November 21, 2013
    Applicant: FUJITSU LIMITED
    Inventor: William W. WALKER
  • Patent number: 8432995
    Abstract: In one embodiment, a method includes receiving input data bits over data channels; receiving deskew channel bits constituting frames that each comprise ones of the input data bits; determining frame boundaries; mapping each of the input data bits in each of the frames to one of the data channels; for each set of the frames, comparing the input data bits in the set with the input data bits in the corresponding input data words; determining relative delays among the data channels and the deskew channel; when non-zero delays are determined, rearranging the input data bits to reduce the delays; and when it is determined that one or more of the data channels have a delay of greater than a predetermined number of data-channel clock periods relative to a particular data channel, delaying input data bits in the particular data channel by an additional number of input data bits.
    Type: Grant
    Filed: July 21, 2010
    Date of Patent: April 30, 2013
    Assignee: Fujitsu Limited
    Inventors: Samir Parikh, Nikola Nedovic, William W. Walker
  • Patent number: 8411782
    Abstract: In one embodiment, a method includes receiving input data bits at a collective data rate, the input data bits being grouped into a plurality of input data words, the input data bits of each of the input data words being received from n parallel input-data-bit streams, each of the n parallel input-data-bit streams having a stream data rate that is 1/n of the collective data rate, each of the input data words comprising n consecutive ones of the input data bits; selecting particular input data bits; and generating a k-bit deskew channel with the selected input data bits, the deskew channel comprising a number of frames, each of the frames comprising x input data bits from one or more input data words and one or more framing bits. In another embodiment, a method includes using such a deskew channel to determine relative delays between data channels and the deskew channel.
    Type: Grant
    Filed: July 29, 2009
    Date of Patent: April 2, 2013
    Assignee: Fujitsu Limited
    Inventors: Samir Parikh, William W. Walker, Nestor Tzartzanis
  • Patent number: 8300753
    Abstract: In one embodiment, a method includes accessing a reference clock having a reference clock frequency and reference clock phase; generating an output clock having an output clock phase and output clock frequency that is a function of an analog control voltage setting and a frequency gain curve; fixing the analog control voltage setting to a predetermined voltage; selecting one of the frequency gain curves within a predetermined frequency range of the reference clock frequency at the analog control voltage setting; adjusting the analog control voltage setting to adjust the output clock frequency to be within another predetermined frequency range of the reference clock frequency; and adjusting the output clock phase to be within a predetermined phase range of an input data phase of the input data stream.
    Type: Grant
    Filed: July 27, 2009
    Date of Patent: October 30, 2012
    Assignee: Fujitsu Limited
    Inventors: Nikola Nedovic, Nestor Tzartzanis, William W. Walker
  • Patent number: 8300754
    Abstract: In one embodiment, a method includes receiving first and second input streams comprising first and second input data bits, respectively. The method includes generating first and second recovered clocks based on the first and second input streams, respectively. The method includes retiming and demultiplexing the first and second input data bits to generate n first recovered streams and n second recovered streams, respectively, each comprising first and second recovered data bits, respectively. The method further includes determining a phase difference between the first and second recovered clocks; aligning the first recovered data bits with the second recovered data bits based at least in part on a value of n and the phase difference; combining the first and second recovered data bits to generate an output stream; and retiming the first and second recovered data bits in the output stream based on either the first or second recovered clock.
    Type: Grant
    Filed: July 27, 2009
    Date of Patent: October 30, 2012
    Assignee: Fujitsu Limited
    Inventors: Nikola Nedovic, Nestor Tzartzanis, William W. Walker, Hirotaka Tamura
  • Patent number: 8255196
    Abstract: A system and method for constructing a clock tree based on replica stages is described. The system and method may comprise determining a size of an input buffer for driving a load capacitance of the output buffer based on a fanout, determining a wire width and a wire length based on the size of the output buffer, the fanout and a replica stage mathematical model, and connecting the output buffer and the corresponding input buffer to a conductor routed on one or more predetermined metal layers and having the wire length and the wire width. The conductor is placed within ground shields having a fixed width.
    Type: Grant
    Filed: August 25, 2008
    Date of Patent: August 28, 2012
    Assignee: Fujitsu Limited
    Inventors: William W. Walker, Subodh M. Reddy, Ranjeez Murgai