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Expired Canadian patentCanada

Line feed circuit including negative impedance circuit

CA 1190682 A · Owner: Nortel Networks Limited · Inventors: Keriakos, Magdy H.; Rosenbaum, Stanley D.

CIPO record

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Abstract From the Canadian patent

Abstract of the Disclosure, Communication lines for example telephone loop circuits are typically terminated with line feed circuits such that d.c. and a.c. terminating impedances are dissimilar. The line feed circuit includes tip and ring feed resistors of similar ohmic values for supplying the communcation line with energizing current. An a.c. terminating impedance of greater ohmic value than the d.c. terminating resistance is provided by a negative impedance circuit which is a.c. coupled across the communication line, in shunt with the feed resistors. -i-

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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.

Why it's free to use

  • Granted July 16, 1985. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended July 16, 2002.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledJanuary 31, 1983
GrantedJuly 16, 1985
Term endedJuly 16, 2002
Patent numberCA 1190682 A
Classification (IPC)H04M7/00 +1 more

Timeline

Timeline From CIPO dates

1984198619881990199219941996199820002002Application filedJan 31, 1983Patent grantedJuly 16, 1985Term endedJuly 16, 2002

Sources & verification

Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.