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Expired Canadian patentCanada

Two-stage high-resolution digital-to-analog converter

CA 1234921 A · Owner: Analog Devices, Incorporated · Inventors: Holloway, Peter R.

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

935.074, ABSTRACT OF THE DISCLOSURE, A 16-bit D/A converter formed on a single monolithic IC chip and having two cascaded stages each including a 256-R resistor-string DAC. The first stage employs a switch selector system capable of selecting any two adjacent taps of the resistor string to produce a segment voltage to be applied across the second stage resistor string. The resistor strings are formed as elongate thin film strips configured as a single, unbent body having integral voltage tap nipples evenly-spaced along both sides of the strip. Buffer amplifiers between the cascaded stages incorporate NMOS and PMOS-cascoded bipolar current sources in a non-epitaxial structure on a P-type …

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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 April 5, 1988. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended April 5, 2005.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledFebruary 18, 1985
GrantedApril 5, 1988
Term endedApril 5, 2005
Patent numberCA 1234921 A
Classification (IPC)H04M1/68 +2 more

Timeline

Timeline From CIPO dates

1986198819901992199419961998200020022004Application filedFeb 18, 1985Patent grantedApril 5, 1988Term endedApril 5, 2005

Sources & verification

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