The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 02, 1988
Filed:
Aug. 20, 1986
Koji Nishio, Tokyo, JP;
Yasuo Shirai, Tokyo, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
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.