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Test ring oscillator

  • US 5,811,983 A
  • Filed: 09/03/1996
  • Issued: 09/22/1998
  • Est. Priority Date: 09/03/1996
  • Status: Expired due to Term
First Claim
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1. A test apparatus for quantifying parasitics on a microprocessor, the test apparatus comprising:

  • a plurality of first gate stages, said first gate stages having a first portion and a second portion;

    a plurality of second gate stages, said second gate stages having a first portion and a second portion, said second gate stages connected in between said plurality of first gate stages, wherein said plurality of first gate stages and said plurality of second gate stages are connected together to form a ring oscillator, said ring oscillator producing a periodic signal;

    a first signal path within said ring oscillator, said first signal path flowing through said first portion of said plurality of first gate stages and said first portion of said plurality of second gate stages;

    a second signal path within said ring oscillator, said second signal path flowing through said second portion of said plurality of first gate stages and said second portion of said plurality of second gate stages;

    a test node, connected between one of said plurality of first gate stages and one of said plurality of second gate stages, for monitoring said periodic signal produced by said ring oscillator;

    wherein the high portion of said periodic signal produced by said ring oscillator at said test node flows through said first signal path, and the low portion of said periodic signal produced by said ring oscillator at said test node flows through said second signal path;

    whereby the relationship of said high portion and said low portion of said periodic signal at said test node corresponds to the difference between said parasitics of said first signal path and said second signal path.

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