Patents by Inventor Yasuo Shirai

Yasuo Shirai 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).

  • Voice circuit of telephone
    Patent number: 4723278
    Abstract: A voice circuit of a telephone is provided with a differential amplifier and an impedance setting circuit. An output of an amplifier to amplify an output signal of a transmitter is supplied to the inverting input terminal of the differential amplifier. An output of the impedance setting circuit is supplied to the noninverting input terminal of the differential amplifier. An output signal of the differential amplifier is supplied to a line driver. A positive feedback loop is constituted by the differential amplifier, line driver, telephone line, and impedance setting circuit. By controlling a feedback amount in this positive feedback loop, an AC impedance is controlled.
    Type: Grant
    Filed: August 20, 1986
    Date of Patent: February 2, 1988
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Koji Nishio, Yasuo Shirai