An Improved VLSI Test Economics Analysis System - Laboratory for ...

An Improved VLSI Test Economics Analysis System - Laboratory for ... An Improved VLSI Test Economics Analysis System - Laboratory for ...

larc.ee.nthu.edu.tw
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12.07.2015 Views

Chapter 5ConclusionsWe have shown that if we select suitable test strategy for the design, the prot will greatlyincrease. Economic models had been developed to help nd the optimal test strategy. Weproposed four economic models, a set of circuit parameters, and a test methodologies library.Base on the previous works, a quality model had been added to provide more accurateestimation value of test related parameters, such as fault coverage, yield and defect level.The whole system now includes four models: Cost Model, Time Model, Quality Model andMarket Life Model. Cost Model estimates the total cost and Market Life Model estimatesthe revenue. Moreover, Time Model estimate the time related parameters. Besides, in thecircuit description, many suggestion and heuristics have been proposed to help estimatecircuit parameters which are hard to obtain.In the system, the new version of ESTEEM provides more security for users data. Thesystem uses Perl, Java and Javascript languages and integrates web server, SQL server, andCGI programs. This system provides more friendly users interface, such as le manager,model editor, and result display. Besides, a more powerful analysis engine had been developed,so user can easily add new equations or modify proposed models to t the conditionof their companies.In addition, we had done some experiments to obtain eects of scan design. The ISCAS'89benchmark circuits were applied to sequential ATPG and random pattern fault simulatorto nd the relation between fault coverage and test length. Then, ISCAS'89 SCAN circuitswere applied to combinational ATPG to obtain similar relation. The relation of three designmethods: sequential ATPG, random pattern, and scan were compared. Moreover, ISCAS'8956

circuits were translated to Verilog format for synthesis. The synthesized area of ISCAS'89and its scan version were compared, too.Finally, an IEEE 1149.5 MTM-Bus slave module chip is analyzed by our system. Theresult shows that the DFT prot will greatly increase if DFT is used, since it saves thedevelopment time and shortens time to market. Besides, by comparing dierent volumes forthe same case, we found a threshold volume. The total cost with DFT is lower than thatwithout DFT under this threshold volume.This is an on-going project, where modeling the eect of more test methodologies, performanceimpact of DFT, more realist models developed from the collected data will be donein the future. Beside, optimization and auto learning capability will be investigated.57

Chapter 5ConclusionsWe have shown that if we select suitable test strategy <strong>for</strong> the design, the prot will greatlyincrease. Economic models had been developed to help nd the optimal test strategy. Weproposed four economic models, a set of circuit parameters, and a test methodologies library.Base on the previous works, a quality model had been added to provide more accurateestimation value of test related parameters, such as fault coverage, yield and defect level.The whole system now includes four models: Cost Model, Time Model, Quality Model andMarket Life Model. Cost Model estimates the total cost and Market Life Model estimatesthe revenue. Moreover, Time Model estimate the time related parameters. Besides, in thecircuit description, many suggestion and heuristics have been proposed to help estimatecircuit parameters which are hard to obtain.In the system, the new version of ESTEEM provides more security <strong>for</strong> users data. Thesystem uses Perl, Java and Javascript languages and integrates web server, SQL server, andCGI programs. This system provides more friendly users interface, such as le manager,model editor, and result display. Besides, a more powerful analysis engine had been developed,so user can easily add new equations or modify proposed models to t the conditionof their companies.In addition, we had done some experiments to obtain eects of scan design. The ISCAS'89benchmark circuits were applied to sequential ATPG and random pattern fault simulatorto nd the relation between fault coverage and test length. Then, ISCAS'89 SCAN circuitswere applied to combinational ATPG to obtain similar relation. The relation of three designmethods: sequential ATPG, random pattern, and scan were compared. Moreover, ISCAS'8956

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