Type of Document Master's Thesis Author Donglikar, Swapneel B Author's Email Address email@example.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 Keywords
- Test Application Time Reduction
- Test Data Volume Reduction
- Random Access Scan
- Design for Test
- Illinois Scan
Date of Defense 2009-06-26 Availability restricted AbstractHigh 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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