Compressed and dynamic fault dictionaries for fault isolation
Ryan, Paul George
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https://hdl.handle.net/2142/23250
Description
Title
Compressed and dynamic fault dictionaries for fault isolation
Author(s)
Ryan, Paul George
Issue Date
1994
Doctoral Committee Chair(s)
Fuchs, W. Kent
Department of Study
Electrical and Computer Engineering
Discipline
Electrical and Computer Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Electronics and Electrical
Language
eng
Abstract
This thesis addresses many of the issues that have in the past limited the use of fault dictionaries for VLSI fault isolation. Dictionary formats have been analyzed, and a new, more accurate matching algorithm has been developed. Alternative techniques for compressing fault dictionaries have been investigated to address size and computation cost issues. Two new compression algorithms are presented. List Splitting creates fault dictionaries with a single full fault simulation and provides for rapidly estimating the diagnostic capabilities of a test set. Sequential compression makes no approximations for sequential circuits and thus loses no resolution; however, it costs more than List Splitting, requiring two fault simulations.
Dictionary compression techniques are compared by the size, computation costs and diagnostic resolution of the compressed dictionaries. Results are given for combinational and sequential benchmark circuits, both ISCAS and non-ISCAS. For combinational circuits, List Splitting provides an inexpensive way to produce a small, full resolution fault dictionary. For sequential circuits, List Splitting is effective in compression but does not always provide full resolution. Sequential and Compact provide full resolution, with increased computation costs. When resolution loss is acceptable, Drop on K and a fault grade dictionary have lower simulation costs than a single full simulation.
A new, dynamic two-stage fault isolation process for sequential random logic VLSI circuits is also described in this thesis, along with the two new types of fault dictionaries it uses, Limited and Dynamic dictionaries. The first stage of this process uses a limited fault dictionary to produce a small list of good candidate faults, and the second stage uses dynamic dictionaries to distinguish those faults. This provides adequate resolution for modeled faults, while avoiding a full dictionary's size-related costs.
Two-stage fault isolation has been implemented in simulation for combinational and sequential circuits (both ISCAS and non-ISCAS), and computation time, storage space and resolution have been evaluated. It has also been applied to two industrial circuits, successfully diagnosing both manually injected defects and defects in production chips.
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