Patents by Inventor Yasuyuki Yufu

Yasuyuki Yufu 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).

  • Variable attenuator device having substantially constant impedance
    Patent number: 6888419
    Abstract: An attenuator of the current invention allows the adjustment in attenuation at a constant impedance level. The attenuator includes at least three variable resistors. Two of the three variable resistors have the substantially same linear resistance characteristics and are controlled in a substantially identical manner. One of the three variable resistors has a non-linear resistance characteristic and is controlled concurrently with the above two variable resistors. As a result of the above resistance characteristics and control, the attenuation is adjusted with respect to the resistance while impedance is maintained at a constant level.
    Type: Grant
    Filed: March 22, 2002
    Date of Patent: May 3, 2005
    Assignee: Hitachi Kokusai Electric, Inc.
    Inventors: Yasuyuki Yufu, Kotaro Takenaga
  • Variable attenuator device having substantially constant impedance
    Publication number: 20030030507
    Abstract: An attenuator of the current invention allows the adjustment in attenuation at a constant impedance level. The attenuator includes at least three variable resistors. Two of the three variable resistors have the substantially same linear resistance characteristics and are controlled in a substantially identical manner. One of the three variable resistors has a non-linear resistance characteristic and is controlled concurrently with the above two variable resistors. As a result of the above resistance characteristics and control, the attenuation is adjusted with respect to the resistance while impedance is maintained at a constant level.
    Type: Application
    Filed: March 22, 2002
    Publication date: February 13, 2003
    Inventors: Yasuyuki Yufu, Kotaro Takenaga