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Browse Prior Art Database

Low-Cost Array Built-In Self-Test Data Comparison for Embedded Arrays

IP.com Disclosure Number: IPCOM000116923D
Original Publication Date: 1995-Nov-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Day, LL: AUTHOR [+6]

Abstract

Low-cost effective ways to compare array built-in self-test data of embedded arrays and to allow for implementing array redundancy scheme with little hardware and no additional tester data is disclosed.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 58% of the total text.

Low-Cost Array Built-In Self-Test Data Comparison for Embedded Arrays

      Low-cost effective ways to compare array built-in self-test
data of embedded arrays and to allow for implementing array
redundancy scheme with little hardware and no additional tester data
is disclosed.

      Array-Built-In-Selftest (ABIST) commonly experiences problems
of high volume of READ/Expect data or substantial amount of hardware
to generate expect data for on-chip comparison.  Either approach can
be very costly.

      For example, ABIST uses scan-chains to send write data and
receive read data in a serial fashion, gate the read data off chip
and then compare with expect data on the tester.  This approach is
very data-volume intensive.  A common alternative is to put
additional logic on chip to generate the expect data for comparison
which is a substantial area overhead.

      The solution to the above problems is a scheme which takes
advantage of data regularity to reduce expect data generation and
data volume.  This scheme, when applied to a general case (Fig. 1),
takes advantage of array application which uses multiple copies of
arrays to form a macro such as D(data)-cache or I(instruction)-cache.
When at least one of the identical arrays is defect free (passes
ABIST), the output (serial bit stream) of the good array can be
exclusive-ORed with the bad array in a serial bit fashion.  The
output will be made observable for the tester.  When the outputs of
array macr...