Title page for ETD etd-07132009-232205

Type of Document Master's Thesis
Author Donglikar, Swapneel B
Author's Email Address getswapnil@gmail.com
URN etd-07132009-232205
Title Design for Testability Techniques to Optimize VLSI Test Cost
Degree Master of Science
Department Electrical and Computer Engineering
Advisory Committee
Advisor Name Title
Hsiao, Michael S. Committee Chair
Abbott, A. Lynn Committee Member
Huang, Chao Committee Member
  • Test Application Time Reduction
  • Test Data Volume Reduction
  • Random Access Scan
  • Design for Test
  • Illinois Scan
Date of Defense 2009-06-26
Availability restricted
High test data volume and long test application time are two major concerns for testing

scan based circuits. The Illinois Scan (ILS) architecture has been shown to be effective

in addressing both these issues. The ILS achieves a high degree of test data compression

thereby reducing both the test data volume and test application time. The degree of test

data volume reduction depends on the fault coverage achievable in the broadcast mode.

However, the fault coverage achieved in the broadcast mode of ILS architecture depends

on the actual configuration of individual scan chains, i.e., the number of chains and the

mapping of the individual flip-flops of the circuit to the respective scan chain positions.

Current methods for constructing scan chains in ILS are either ad-hoc or use test pattern

information from an a-priori automatic test pattern generation (ATPG) run. In this thesis,

we present novel low cost techniques to construct ILS scan configuration for a given design.

These techniques efficiently utilize the circuit topology information and try to optimize the

flip-flop assignment to a scan chain location without much compromise in the fault coverage

in the broadcast mode. Thus, they eliminate the need of an a-priori ATPG run or any

test set information. In addition, we also propose a new scan architecture which combines

the broadcast mode of ILS and Random Access Scan architecture to enable further test

volume reduction on and above effectively configured conventional ILS architecture using

the aforementioned heuristics with reasonable area overhead. Experimental results on the

ISCAS’89 benchmark circuits show that the proposed ILS configuration methods can achieve

on an average 5% more fault coverage in the broadcast mode and on average 15% more test

data volume and test application time reduction than existing methods. The proposed new

architecture achieves, on an average, 9% and 33% additional test data volume and test

application time reduction respectively on top of our proposed ILS configuration heuristics.

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