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Expired Canadian patentCanada

Amplifier circuit using feedback load

CA 2003401 C · Owner: Ishihara, Noboru · Inventors: Ishihara, Noboru; Ichino, Haruhiko

CIPO record

Overview

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Its claims, description and drawings are in the Canadian Patents Database.

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Abstract From the Canadian patent

An amplifier circuit of this invention includes a first-stage amplifier, an amplifier element connected to the output terminal of the first-stage amplifier as a feedback load, and a further amplifier element connected between the output and input terminals of the amplifier element, and performs negative feedback through a load of the first-stage amplifier. As the amplifier element a, transistor is used, and as the further amplifier element an emitter-follower transistor is used.

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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

  • Filed November 20, 1989 and granted March 15, 1994. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended November 20, 2009.
  • A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 20, 2011.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledNovember 20, 1989
GrantedMarch 15, 1994
Term endedNovember 20, 2009
Patent numberCA 2003401 C
Classification (IPC)H03F3/45

Timeline

Timeline From CIPO dates

1990199219941996199820002002200420062008Application filedNov 20, 1989Patent grantedMarch 15, 1994Term endedNov 20, 2009

Sources & verification

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