Patents by Inventor Hirotaka Tamura

Hirotaka Tamura 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).

  • Publication number: 20110006850
    Abstract: A clock signal distributing device includes a plurality of LC resonant oscillators, each resonating at a frequency conforming to values of a first inductor and a first capacitor to oscillate a signal, an injection locked LC resonant oscillator that resonates at a frequency conforming to values of a second inductor and a second capacitor to oscillate a signal which is synchronous with an input clock signal, and transmission lines that connect oscillation nodes of the plurality of LC resonant oscillators and the injection locked LC resonant oscillator with one another.
    Type: Application
    Filed: June 23, 2010
    Publication date: January 13, 2011
    Applicant: FUJITSU LIMITED
    Inventors: Takayuki SHIBASAKI, Hirotaka TAMURA
  • Publication number: 20110002374
    Abstract: A receiver circuit includes: an equalization circuit that equalizes a first signal to obtain a second signal, and adjusts a characteristic of an equalization in accordance with an error between the second signal and a third signal; and a first offset adjustment circuit that adjusts an offset of the first signal in accordance with an error signal indicating the error.
    Type: Application
    Filed: June 29, 2010
    Publication date: January 6, 2011
    Applicant: FUJITSU LIMITED
    Inventors: Masaya KIBUNE, Hirotaka Tamura
  • Patent number: 7863948
    Abstract: A first frequency dividing circuit and a second frequency dividing circuit are provided, and these circuits frequency-divide two-phase external clocks injected from an external part, to output four-phase clocks with phase guarantee. Each of the frequency dividing circuits includes a mixer, an adding circuit, and a phase circuit. The first frequency dividing circuit and the second frequency dividing circuit are coupled in loop shape via a first coupling circuit and a second coupling circuit. The first coupling circuit receives a first output signal of the first frequency dividing circuit to output a second external input signal to the second frequency dividing circuit, and the second coupling circuit receives a second output signal of the second frequency dividing circuit to output a first external input signal to the first frequency dividing circuit, and a clock frequency dividing circuit with a high loop gain and a wide lock range can be realized.
    Type: Grant
    Filed: August 27, 2008
    Date of Patent: January 4, 2011
    Assignee: Fujitsu Limited
    Inventors: Hisakatsu Yamaguchi, Kouichi Kanda, Junji Ogawa, Hirotaka Tamura
  • Patent number: 7863987
    Abstract: LC resonant voltage control oscillators are adopted as voltage control oscillators for the purpose of providing a clock generating and distributing apparatus that can generate and distribute a clock signal of high precision even in a high-frequency region of several giga hertz or higher, and of providing a distributive VCO-type clock generating and distributing apparatus in which voltage control oscillators oscillate in the same phase, and which can generate a clock signal of a desired frequency and distributes a high-frequency clock signal to each part within a chip more stably even in a high-frequency region reaching 20 GHz. Furthermore, an inductor component of a wire connecting the oscillation nodes of the oscillators is made relatively small, or the LC resonant oscillators are oscillated in synchronization by using injection locking, whereby the LC resonant voltage control oscillators stably oscillate in the same phase.
    Type: Grant
    Filed: March 23, 2006
    Date of Patent: January 4, 2011
    Assignee: Fujitsu Limited
    Inventors: Kouichi Kanda, Hirotaka Tamura, Hisakatsu Yamaguchi, Junji Ogawa
  • Patent number: 7826497
    Abstract: A data receiving circuit has a data input terminal, a conversion circuit converting an input signal received via the data input terminal, and a decision circuit making a decision on an output of the conversion circuit. The conversion circuit has a demultiplexer converting the input signal into a signal of a lower frequency than the frequency thereof at the data input terminal, and an output of the demultiplexer is obtained at the drain side of each of a plurality of first transistors having a common source.
    Type: Grant
    Filed: December 26, 2002
    Date of Patent: November 2, 2010
    Assignee: Fujitsu Limited
    Inventors: Yoshiyasu Doi, Hirotaka Tamura
  • Patent number: 7822403
    Abstract: A receiver has an offset application circuit for applying a known offset to an input signal, and a decision circuit for comparing the offset-applied input signal with a reference voltage. The level of the input signal is determined based on the known offset and on the result output from the decision circuit. With this configuration, a large common mode voltage can be eliminated in a circuit used for signal transmission.
    Type: Grant
    Filed: June 4, 2008
    Date of Patent: October 26, 2010
    Assignee: Fujitsu Limited
    Inventor: Hirotaka Tamura
  • Publication number: 20100246734
    Abstract: A receiver that receives a train of a plurality of symbols representing digital data, includes: an isolated pulse detector that detects whether the digital data includes an isolated pulse in the symbol train, respectively; a phase detector that detects a timing at which the level of the symbols changes; a symbol value converter that converts the symbols into logical values on the basis of the timing detected by the phase detector; and a data selector that selects a logical value of the isolated pulse instead of the logical value converted by the symbol value converter when the isolated pulse detector detects the digital data containing the isolated pulse.
    Type: Application
    Filed: March 24, 2010
    Publication date: September 30, 2010
    Applicant: FUJITSU LIMITED
    Inventors: Hirotaka TAMURA, Masaya Kibune
  • Patent number: 7786785
    Abstract: There are provided a peaking detection part detecting a peaking amount in an output part of an inductor peaking circuit and a control signal generation part varying a circuit parameter of the inductor peaking circuit based on the peaking amount detected by the peaking detection part. Particularly, the inductor peaking circuit has inductors and resistors inserted in series between the output part and a power supply, and capacitances coupled in parallel between the output part and an earth (GND), and depending on respective values of these inductors, resistors and capacitances, it is possible to suppress a peaking generated in the output part.
    Type: Grant
    Filed: September 26, 2008
    Date of Patent: August 31, 2010
    Assignee: Fujitsu Limited
    Inventors: Kouichi Kanda, Hirotaka Tamura, Hisakatsu Yamaguchi, Junji Ogawa
  • Publication number: 20100202578
    Abstract: A clock generation circuit includes: a first determination circuit that detects an input signal at a first phase position based on first frequency signal; a second determination circuit that detects the input signal at a second phase position based on second frequency signal; a phase detector that compares output of the first determination circuit and output of the second determination circuit; a first summing circuit which sums comparison result and first control signal; a second summing circuit which sums comparison result and second control signal; a first voltage controlled oscillation circuit which receives output of the first summing circuit and outputs the first frequency signal; a second voltage controlled oscillation circuit which received output of the second summing circuit and outputs the second frequency signal; and a phase adjustment circuit which generates first control signal and second control signal based on first frequency signal and second frequency signal.
    Type: Application
    Filed: December 8, 2009
    Publication date: August 12, 2010
    Applicant: FUJITSU LIMITED
    Inventors: Yasumoto TOMITA, Masaya Kibune, Hirotaka Tamura
  • Publication number: 20100141306
    Abstract: A parallel-serial conversion circuit includes: a plurality of data terminals each receiving a data signal; a selection circuit configured to select at least one of the data signals received through the plurality of data terminals; a first latch circuit configured to latch an output from the selection circuit based on a clock signal; a replica selection circuit configured to select one of a plurality of signals and output the selected signal; and a timing-signal generating circuit configured to generate a timing signal for controlling the selection circuit based on the output from the replica selection circuit, wherein the output from the replica selection circuit is latched based on the clock signal.
    Type: Application
    Filed: November 17, 2009
    Publication date: June 10, 2010
    Applicant: FUJITSU LIMITED
    Inventors: Yoshiyasu DOI, Hirotaka Tamura
  • Publication number: 20100127906
    Abstract: A data recovery circuit includes an analog-digital converter creating a digital code sequence, a phase detector calculating a position of a crossing point from the digital code sequence, a phase estimator acquiring a presumed position of a data center point of a data sequence based on the position of the crossing point, and a data determining circuit extracting the sequence of data determination values from the digital code sequence based on the position of the crossing point and the presumed position of the data center point.
    Type: Application
    Filed: November 19, 2009
    Publication date: May 27, 2010
    Applicant: FUJITSU LIMITED
    Inventors: Hisakatsu YAMAGUCHI, Hirotaka Tamura, Masaya Kibune
  • Publication number: 20100104057
    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: Application
    Filed: July 27, 2009
    Publication date: April 29, 2010
    Applicant: Fujitsu Limited
    Inventors: Nikola Nedovic, Nestor Tzartzanis, William W. Walker, Hirotaka Tamura
  • Publication number: 20100061498
    Abstract: A receiving circuit includes a clock generation circuit that generates a clock signal, an integration filter that stores a signal potential of an input signal and generates a first storage potential in a period in which the clock signal indicates one logic, a first analog-to-digital circuit that converts the first storage potential into a first digital value, and a data determination circuit that determines a logic of the input signal on a basis of the first digital value.
    Type: Application
    Filed: September 9, 2009
    Publication date: March 11, 2010
    Applicant: FUJITSU LIMITED
    Inventors: Yoshiyasu Doi, Hirotaka Tamura
  • Publication number: 20100019827
    Abstract: An integrated circuit includes a bypass signal path exchanging, between transceivers which are included in the integrated circuit, a signal transmitted/received between a transceiver of the transceivers and an internal logic circuit which processes data being input/output by transceiver with bypassing the internal logic circuit, a switch switching a pathway of the bypass signal path, and a switch changeover controller transferring a switch control signal that performs a changeover of the switch.
    Type: Application
    Filed: September 29, 2006
    Publication date: January 28, 2010
    Applicant: FUJITSU LIMITED
    Inventors: Hirotaka Tamura, Masaya Kibune
  • Patent number: 7653169
    Abstract: In order to provide a timing adjustment circuit capable of transmitting/receiving data without being affected by process unevenness and power voltage/temperature fluctuations even at a high data transfer rate, the phase of data outputted by a data transmitting unit is compared with the phase of a clock for regulating a data receiving timing of a data receiving unit, and the phase of a clock for regulating a data transmitting timing of the data transmitting unit is adjusted according to the comparison result.
    Type: Grant
    Filed: February 27, 2006
    Date of Patent: January 26, 2010
    Assignee: Fujitsu Limited
    Inventors: Hisakatsu Yamaguchi, Kouichi Kanda, Junji Ogawa, Hirotaka Tamura
  • Publication number: 20100011265
    Abstract: An integrated circuit chip includes a plurality of two-way transceivers capable of simultaneously transmitting and receiving signals, a switch circuit coupled to the plurality of two-way transceivers and to a given node to provide switchable couplings between the plurality of two-way transceivers and the given node, an interconnection information storage unit to store interconnection information, and a control circuit to set the couplings of the switch circuit in response to the interconnection information.
    Type: Application
    Filed: September 18, 2009
    Publication date: January 14, 2010
    Applicant: FUJITSU LIMITED
    Inventors: Hirotaka Tamura, Masaya Kibune
  • Publication number: 20090225900
    Abstract: A data transmitting circuit includes a reflection suppressive component generating circuit for generating a reflection suppressive component for suppressing the reflection caused by the discontinuity in the characteristic impedance on a transmission line, and a data output circuit for amplifying the reflection suppressive component and the data to be currently transmitted to a receiving side and outputting them to the transmission line.
    Type: Application
    Filed: February 25, 2009
    Publication date: September 10, 2009
    Applicant: FUJITSU LIMITED
    Inventors: Hisakatsu YAMAGUCHI, Yoshiyasu Doi, Hirotaka Tamura
  • Publication number: 20090220029
    Abstract: A clock recovery circuit has a boundary detection circuit detecting a boundary in an input signal in accordance with a first signal, and performs recovery of a clock by controlling the timing of the first signal in accordance with the detected boundary. The clock recovery circuit has a boundary detection timing varying circuit and a variation reducing circuit. The boundary detection timing varying circuit dynamically varies boundary detection timing in the boundary detection circuit by applying a variation to the first signal, and the variation reducing circuit reduces a phase variation occurring in the recovered clock in accordance with the dynamic variation of the boundary detection timing performed by the boundary detection timing varying circuit.
    Type: Application
    Filed: March 9, 2009
    Publication date: September 3, 2009
    Applicant: FUJITSU LIMITED
    Inventors: Hisakatsu YAMAGUCHI, Hirotaka Tamura
  • Publication number: 20090195281
    Abstract: A semiconductor integrated circuit device has a command decoder for issuing a control command in accordance with a supplied control signal, a DRAM core, and a timing adjusting circuit for supplying the control command, set active for a predetermined period, as a DRAM control signal to the DRAM core. The timing adjusting circuit generates n different clocks that are respectively shifted in phase with respect to a supplied reference clock, and generates the DRAM control signal by setting the control command active in a prescribed operation cycle for only a period starting at a first predetermined clock pulse of a first clock of the n clocks and ending at a second predetermined clock pulse of a second clock of the n clocks. In this way, timing design with relatively high accuracy of adjustment can be done in a short period.
    Type: Application
    Filed: January 23, 2009
    Publication date: August 6, 2009
    Applicant: FUJITSU LIMITED
    Inventors: Hirotaka Tamura, Hisakatsu Yamaguchi, Shigetoshi Wakayama, Kohtaroh Gotoh, Junji Ogawa
  • Publication number: 20090179674
    Abstract: A phase-combining circuit for combining cyclic timing waveforms that have been phase-controlled by control signals based on three or more input signals of different phases, has a weight signal generating circuit and a weighting circuit. The weight signal generating circuit generates weights according to the control signals, and the weighting circuit gives the weights to the respective input signals, with a positive or negative polarity for each one signal.
    Type: Application
    Filed: February 2, 2009
    Publication date: July 16, 2009
    Applicant: FUJITSU LIMITED
    Inventors: Hirotaka Tamura, Masaya Kibune