Browse Prior Art Database

Signal Measurement Method for Flip-Chip Attach LSI

IP.com Disclosure Number: IPCOM000115787D
Original Publication Date: 1995-Jun-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Mashima, I: AUTHOR

Abstract

A signal measurement method for flip-chip-attach LSI is disclosed to improve LSI signal observability with significantly fewer test-points by utilizing boundary-scan logic and internal tri-state buffers. This method will solve problems in measuring signals of flip-chip-attach LSI where the signals are not probable on LSI. This idea is applicable only when boundary-scan concept is incorporated.

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Signal Measurement Method for Flip-Chip Attach LSI

      A signal measurement method for flip-chip-attach LSI is
disclosed to improve LSI signal observability with significantly
fewer test-points by utilizing boundary-scan logic and internal
tri-state buffers.  This method will solve problems in measuring
signals of flip-chip-attach LSI where the signals are not probable on
LSI.  This idea is applicable only when boundary-scan concept is
incorporated.

      The basic idea is to insert tri-state buffers in LSI design and
connect each of the need-to-observe signals to the input of one of
the inserted tri-state buffers.  The output of these buffers are
dot-wired and brought out to the LSI observation point (test point).
The key idea is to utilize boundary-scan latches with "through mode"
when the LSI is functioning and control the latches from LSI I/O's in
order to select one of the need-to-observe signals by enabling one of
the tri-state buffers which is fed by the need-to-observe signal.

      Generally, multiple tri-state buffers can be dot-wired.  Then
the test points needed for LSI signal measurement can be
significantly reduced.  (Without this idea, the number of test points
is equal to the number of need-to-observe signals).