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:
Jan. 30, 1990
Filed:
Mar. 26, 1987
Morris L Minch, Coral Springs, FL (US);
Theodore W Wagner, West Palm Beach, FL (US);
Siemens Corporation, Iselin, NJ (US);
Abstract
A transformerless hybrid circuit arrangement for a subscriber line interface circuit of a telecommunications exchange is disclosed. A preferred embodiment of the hybrid arrangement comprises a first and a second operational amplifier plus a differential amplifier connected together in the following manner: The non-inverting input of the first operational amplifier is connected to a first reference voltage and the output of this amplifier is connected (1) via a first resistor to one wire of the two-wire subscriber line, and (2) via a third resistor to the inverting input of the amplifier. The non-inverting input of the second operational amplifier is connected to a second reference voltage and to the receiving branch of the four-wire line of the telecommunications exchange. The output of this second operational amplifier is connected via a second resistor to the other wire of the two-wire subscriber line, via a fourth resistor to the inverting input thereof and via a fifth resistor to the inverting input of the first operational amplifier. Each of the two inputs of the differential amplifier are connected, via respective resistors, to one wire of the two-wire subscriber line and to the output of that operational amplifier which is connected to the other wire of the two-wire subscriber line. The output of the differential amplifier is connected to the transmitting branch of the four-wire line of the exchange.