Patents by Inventor Masafumi Shigaki

Masafumi Shigaki 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: 7729129
    Abstract: In a package mounting structure for mounting a package on a case, wherein the package internally incorporates at least one of a high-frequency transistor, MIC and MMIC used in the microwave to millimeter-wave band, and a base thereof is formed of metal and serves as ground, an electrically conductive sheet having excellent thermal conductivity and exhibiting restorability and having a size identical with that of the base of the package is laid on the case at a package-bearing location, the package and sheet are fastened together by two or more screws, and the sheet is mounted on the case while it is pressed by a pressing force of 10 N/cm2 or greater owing to fastening.
    Type: Grant
    Filed: October 17, 2007
    Date of Patent: June 1, 2010
    Assignee: Fujitsu Limited
    Inventors: Masafumi Shigaki, Isao Nakazawa, Kazunori Yamanaka
  • Patent number: 7495615
    Abstract: An antenna coupling module for electromagnetically coupling a planar antenna and a planar type oxide superconductive high frequency circuit not reducing the antenna effective area and sharply reducing the signal loss due to coupling, comprised of a planar antenna and a substrate forming a planar superconductive high frequency circuit arranged in a perpendicular direction with respect to the element surface of the planar antenna and having the planar antenna and the superconductive high frequency circuit electromagnetically coupled.
    Type: Grant
    Filed: March 3, 2004
    Date of Patent: February 24, 2009
    Assignee: Fujitsu Limited
    Inventors: Kazunori Yamanaka, Isao Nakazawa, Masafumi Shigaki
  • Publication number: 20080144287
    Abstract: In a package mounting structure for mounting a package on a case, wherein the package internally incorporates at least one of a high-frequency transistor, MIC and MMIC used in the microwave to millimeter-wave band, and a base thereof is formed of metal and serves as ground, an electrically conductive sheet having excellent thermal conductivity and exhibiting restorability and having a size identical with that of the base of the package is laid on the case at a package-bearing location, the package and sheet are fastened together by two or more screws, and the sheet is mounted on the case while it is pressed by a pressing force of 10 N/cm2 or greater owing to fastening.
    Type: Application
    Filed: October 17, 2007
    Publication date: June 19, 2008
    Applicant: FUJITSU LIMITED
    Inventors: Masafumi Shigaki, Isao Nakazawa, Kazunori Yamanaka
  • Patent number: 7379023
    Abstract: An antenna device includes a plane-type antenna element, a heat insulation container for blocking heat entering from the outside, the heat insulation container having a radio-wave window allowing a radio wave to pass therethrough, and housing the plane-type antenna element, a waveguide housed in the heat insulation container and arranged between the radio-wave window and an antenna pattern formation surface of the plane-type antenna element, and cooling means for cooling the plane-type antenna element. The waveguide is shaped and dimensioned so that the directivity of the plane-type antenna element is enhanced, and a superconducting film is used for the antenna pattern of the plane-type antenna element.
    Type: Grant
    Filed: June 16, 2006
    Date of Patent: May 27, 2008
    Assignee: Fujitsu Limited
    Inventors: Kazunori Yamanaka, Masafumi Shigaki, Isao Nakazawa
  • Patent number: 7285429
    Abstract: In a package mounting structure for mounting a package on a case, wherein the package internally incorporates at least one of a high-frequency transistor, MIC and MMIC used in the microwave to millimeter-wave band, and a base thereof is formed of metal and serves as ground, an electrically conductive sheet having excellent thermal conductivity and exhibiting restorability and having a size identical with that of the base of the package is laid on the case at a package-bearing location, the package and sheet are fastened together by two or more screws, and the sheet is mounted on the case while it is pressed by a pressing force of 10 N/cm2 or greater owing to fastening.
    Type: Grant
    Filed: August 27, 2004
    Date of Patent: October 23, 2007
    Assignee: Fujitsu Limited
    Inventors: Masafumi Shigaki, Isao Nakazawa, Kazunori Yamanaka
  • Patent number: 7283855
    Abstract: A dielectric waveguide which comprises a first single crystal magnesium oxide block having a surface of face (001), (100) or (010) and a first copper oxide superconducting film formed on the above-described surface in a c-axis crystal orientation perpendicular to the surface, and a method of production thereof are provided.
    Type: Grant
    Filed: August 26, 2003
    Date of Patent: October 16, 2007
    Assignee: Fujitsu Limited
    Inventors: Kazunori Yamanaka, Akihiko Akasegawa, Masafumi Shigaki, Isao Nakazawa
  • Publication number: 20070001910
    Abstract: An antenna device includes a plane-type antenna element, a heat insulation container for blocking heat entering from the outside, the heat insulation container having a radio-wave window allowing a radio wave to pass therethrough, and housing the plane-type antenna element, a waveguide housed in the heat insulation container and arranged between the radio-wave window and an antenna pattern formation surface of the plane-type antenna element, and cooling means for cooling the plane-type antenna element. The waveguide is shaped and dimensioned so that the directivity of the plane-type antenna element is enhanced, and a superconducting film is used for the antenna pattern of the plane-type antenna element.
    Type: Application
    Filed: June 16, 2006
    Publication date: January 4, 2007
    Applicant: FUJITSU LIMITED
    Inventors: Kazunori Yamanaka, Masafumi Shigaki, Isao Nakazawa
  • Patent number: 6914483
    Abstract: A signal is sampled at a stage following a first amplifier circuit (12, 14, 16) and preceding a second amplifier circuit (20, 22), and the presence or absence of a signal is detected by a detector circuit (30). When the presence of a signal is detected, a gate bias circuit (32) switches a gate bias for FETs in the second amplifier circuit (20, 22) to a normal operating voltage value, and when the signal is no longer detected, the gate bias is switched to a voltage value that reduces power consumption, after a mask time has elapsed. In a distortion feedback-type high-frequency amplifier circuit, a means for cutting off a circuit portion for the adjustment of each of a distortion extracting circuit and an inverse distortion adding circuit is achieved by switching FET gate voltage so as to put the corresponding amplifier in a virtually cutoff condition.
    Type: Grant
    Filed: August 12, 2004
    Date of Patent: July 5, 2005
    Assignee: Fujitsu Limited
    Inventor: Masafumi Shigaki
  • Patent number: 6859029
    Abstract: A monitoring system for high-frequency circuits which minimizes the insertion loss of additional monitoring circuits while requiring only a small space. An input coupler is placed at the input of a high-frequency circuit whose frequency response is to be monitored. The input coupler has a space where a given high-frequency probing signal can propagate, and it combines this propagating signal with a given electrical input signal. The combined signal is processed by the high-frequency circuit, and the resulting signal is supplied to an output coupler. The output coupler has a space for propagation of a high-frequency probing signal component contained in the received combined signal. The output coupler extracts this propagating signal component for the purpose of monitoring.
    Type: Grant
    Filed: July 24, 2003
    Date of Patent: February 22, 2005
    Assignee: Fujitsu Limited
    Inventors: Kazunori Yamanaka, Isao Nakazawa, Masafumi Shigaki, Manabu Kai
  • Publication number: 20050029546
    Abstract: In a package mounting structure for mounting a package on a case, wherein the package internally incorporates at least one of a high-frequency transistor, MIC and MMIC used in the microwave to millimeter-wave band, and a base thereof is formed of metal and serves as ground, an electrically conductive sheet having excellent thermal conductivity and exhibiting restorability and having a size identical with that of the base of the package is laid on the case at a package-bearing location, the package and sheet are fastened together by two or more screws, and the sheet is mounted on the case while it is pressed by a pressing force of 10 N/cm2 or greater owing to fastening.
    Type: Application
    Filed: August 27, 2004
    Publication date: February 10, 2005
    Inventors: Masafumi Shigaki, Isao Nakazawa, Kazunori Yamanaka
  • Publication number: 20050012548
    Abstract: A signal is sampled at a stage following a first amplifier circuit (12, 14, 16) and preceding a second amplifier circuit (20, 22), and the presence or absence of a signal is detected by a detector circuit (30). When the presence of a signal is detected, a gate bias circuit (32) switches a gate bias for FETs in the second amplifier circuit (20, 22) to a normal operating voltage value, and when the signal is no longer detected, the gate bias is switched to a voltage value that reduces power consumption, after a mask time has elapsed. In a distortion feedback-type high-frequency amplifier circuit, a means for cutting off a circuit portion for the adjustment of each of a distortion extracting circuit and an inverse distortion adding circuit is achieved by switching FET gate voltage so as to put the corresponding amplifier in a virtually cutoff condition.
    Type: Application
    Filed: August 12, 2004
    Publication date: January 20, 2005
    Inventor: Masafumi Shigaki
  • Publication number: 20040189533
    Abstract: An antenna coupling module for electromagnetically coupling a planar antenna and a planar type oxide superconductive high frequency circuit not reducing the antenna effective area and sharply reducing the signal loss due to coupling, comprised of a planar antenna and a substrate forming a planar superconductive high frequency circuit arranged in a perpendicular direction with respect to the element surface of the planar antenna and having the planar antenna and the superconductive high frequency circuit electromagnetically coupled.
    Type: Application
    Filed: March 3, 2004
    Publication date: September 30, 2004
    Applicant: FUJITSU LIMITED
    Inventors: Kazunori Yamanaka, Isao Nakazawa, Masafumi Shigaki
  • Publication number: 20040119480
    Abstract: A monitoring system for high-frequency circuits which minimizes the insertion loss of additional monitoring circuits while requiring only a small space. An input coupler is placed at the input of a high-frequency circuit whose frequency response is to be monitored. The input coupler has a space where a given high-frequency probing signal can propagate, and it combines this propagating signal with a given electrical input signal. The combined signal is processed by the high-frequency circuit, and the resulting signal is supplied to an output coupler. The output coupler has a space for propagation of a high-frequency probing signal component contained in the received combined signal. The output coupler extracts this propagating signal component for the purpose of monitoring.
    Type: Application
    Filed: July 24, 2003
    Publication date: June 24, 2004
    Applicant: FUJITSU LIMITED
    Inventors: Kazunori Yamanaka, Isao Nakazawa, Masafumi Shigaki, Manabu Kai
  • Publication number: 20040041656
    Abstract: A dielectric waveguide which comprises a first single crystal magnesium oxide block having a surface of face (001), (100) or (010) and a first copper oxide superconducting film formed on the above-described surface in a c-axis crystal orientation perpendicular to the surface, and a method of production thereof are provided.
    Type: Application
    Filed: August 26, 2003
    Publication date: March 4, 2004
    Applicant: FUJITSU LIMITED
    Inventors: Kazunori Yamanaka, Akihiko Akasegawa, Masafumi Shigaki, Isao Nakazawa
  • Patent number: 6486734
    Abstract: An amplifier apparatus including a first dividing circuit disposed at the input side of an amplifier, for dividing an input signal into a primary signal to be amplified by the amplifier and an auxiliary signal for distortion detection, a distortion compensating signal generating circuit for generating a distortion compensating signal, based on the auxiliary signal and the output of the amplifier, to compensate a distortion component contained in the output of the primary amplifier and inputting the generated signal into the amplifier, and a primary signal combining circuit for combining the primary signal obtained by the first dividing circuit 1 with the distortion compensating signal. The result is that even using an auxiliary amplifier whose gain is small or without using such auxiliary amplifier in a feedback system, the distortion component contained in the output of the amplifier can be effectively compensated.
    Type: Grant
    Filed: February 23, 2001
    Date of Patent: November 26, 2002
    Assignee: Fujitsu Limited
    Inventors: Keiichi Oguro, Masafumi Shigaki
  • Patent number: 6377118
    Abstract: A linearizer includes an input terminal, an output terminal, and a field-effect transistor having a gate connected to the input terminal, a drain connected to the output terminal and a source grounded. A supply voltage is supplied through a load circuit to the drain of the transistor. A gate voltage is supplied through a bias line to the gate of the transistor. The transistor is biased at a bias point at which a drain current of the transistor in response to the gate voltage is in an unsaturated region.
    Type: Grant
    Filed: August 30, 1999
    Date of Patent: April 23, 2002
    Assignee: Fujitsu Limited
    Inventors: Masafumi Shigaki, Takao Sasaki
  • Publication number: 20010054932
    Abstract: An amplifier apparatus including a first dividing circuit disposed at the input side of an amplifier, for dividing an input signal into a primary signal to be amplified by the amplifier and an auxiliary signal for distortion detection, a distortion compensating signal generating circuit for generating a distortion compensating signal, based on the auxiliary signal and the output of the amplifier, to compensate a distortion component contained in the output of the primary amplifier and inputting the generated signal into the amplifier, and a primary signal combining circuit for combining the primary signal obtained by the first dividing circuit 1 with the distortion compensating signal. The result is that even using an auxiliary amplifier whose gain is small or without using such auxiliary amplifier in a feedback system, the distortion component contained in the output of the amplifier can be effectively compensated.
    Type: Application
    Filed: February 23, 2001
    Publication date: December 27, 2001
    Inventors: Keiichi Oguro, Masafumi Shigaki
  • Patent number: 4855895
    Abstract: A frequency dividing apparatus having an input signal terminal and a divided signal terminal, whereby a high frequency input to the input signal terminal is divided by a mixer having a first input terminal connected to the input signal terminal having a second input terminal, and having an output terminal connected to the divided signal terminal. A frequency divider is provided having a fixed frequency dividing ratio. The frequency divider has an input terminal connected to the divided signal terminal and an output terminal connected to the second input terminal of the mixer.
    Type: Grant
    Filed: May 19, 1988
    Date of Patent: August 8, 1989
    Assignee: Fujitsu Limited
    Inventors: Masafumi Shigaki, Hiroshi Kurihara, Hidetoshi Nishi
  • Patent number: 4612514
    Abstract: A feedback amplifier circuit includes an inversion circuit, a level shift circuit, and a feedback resistive element. The inversion circuit includes an input active element and a load element connected in cascade with respect to a voltage source. The level shift circuit includes a field effect transistor having a gate connected to the output of the inversion circuit, a diode or diodes, a constant current active load connected in cascade with respect to the voltage source, and the feedback resistive element is connected between the output of the level shift circuit and the input of the inversion circuit.
    Type: Grant
    Filed: March 26, 1984
    Date of Patent: September 16, 1986
    Assignee: Fujitsu Limited
    Inventors: Masafumi Shigaki, Yukio Takeda