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:
Nov. 25, 1997
Filed:
Oct. 27, 1994
Aldo Torazzina, Biassono, IT;
SGS-Thomson Microelectronics S.r.l., Agrate Brianza, IT;
Abstract
A telephone subscriber circuit is coupled via a single galvanic isolation element to provide, from a subscriber apparatus unconnected to the telephone line, on- and off-hook signals to the telephone line and to control transfer of telephonic signals between the subscriber apparatus and the telephone line. The galvanic isolation element is a photocoupler. The subscriber circuit includes a speech circuit coupled to the line through a diode bridge circuit and an electronic switch is connected between the speech circuit and the diode bridge circuit. An input terminal of the speech circuit and a control terminal of the electronic switch are each connected through a voltage-generating circuit and level-translating circuit to an output terminal of the galvanic isolation element.