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Array Diagnostic Method

IP.com Disclosure Number: IPCOM000108320D
Original Publication Date: 1992-May-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Junginger, M: AUTHOR [+4]

Abstract

Two test heads are used in order to diagnose self-test failures in an embedded array. One test head contains a "golden" module, i.e., a module known to be free of faults, and the other test head contains the module under test. An array self-test pattern is repeatedly applied simultaneously to both test heads and the output results compared. Should a difference in outputs be detected, then the location of the array fail can be determined.

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This is the abbreviated version, containing approximately 84% of the total text.

Array Diagnostic Method

       Two test heads are used in order to diagnose self-test
failures in an embedded array.  One test head contains a "golden"
module, i.e., a module known to be free of faults, and the other test
head contains the module under test.  An array self-test pattern is
repeatedly applied simultaneously to both test heads and the output
results compared.  Should a difference in outputs be detected, then
the location of the array fail can be determined.

      The figure shows the apparatus used to test the array. A
programmable random pattern generator (PRPG) 10 is used to produce
the test data.  This is written into an array under test 30 through
SRL chains 50a, 50b, 50c to the addresses given by an address stepper
40.  The data is read out of the array into another SRL chain 50a,
50b, 50c and then into a multiple input signature register (MISR) 20.

      A first test run is carried out by generating patterns and
reading the patterns into and out of a large number of different cell
locations simultaneously in both the golden module and the module
under test.  If the signatures from both the modules are the same
after the test run is completed, then the module under test is free
of faults.

      Alternatively, if the signatures are different, then a fault in
the array is indicated.  Further test runs are carried out, with
differing number of locations tested, until the location at which the
fault occurs is identified. This is giv...