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

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

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The proposed economic models consists of four models: Cost Model, Time Model, MarketLife Model and Quality Model. Besides, we propose a test methodology library to describewhat and how circuit parameters are modied by various <strong>Test</strong> methodologies. Figure 2.2shows relations among circuit description, test methodologies and our four models. Finalresult is prot estimation, which can be given byProf = R , C; (2.8)where C is total cost which is estimated in Cost Model and R is revenue which comes fromMarket Life Model. <strong>An</strong>other result is defect level estimation, which is calculated in QualityModel. Complete estimation need two passes to each model. For the rst pass, we targetestimation on the condition of no DFT applied, and more detailed action of each model isdescribed bellow:Quality Model: It estimates test-related parameters, such as yield, fault coverage, defect level,and test length, from area, gate count, testability, etc., which get from circuit description.The defect level is an important pointer of production quality, and otherresults are transfered to time and cost models.Time Model: This model estimates parameters about time. It receives circuit descriptionand Quality Model parameters, than, estimates design and verication time in development,and test time in wafer test, pre-burn-in test, and nal test. Finally, theresults are transfered to cost model.Cost Model: This model collects parameters from circuit description, Time Model, and QualityModel to calculate total costs <strong>for</strong> prot estimation. Total cost merges three stagecost which are development cost, manufacturing cost, and test cost.Market Life Model: This model uses only its local parameters to estimate revenue, becausewe assume that revenue only comes from market.In the second pass, some circuit parameters and equations in models, such as area, and gatecount, are modied according to the test strategy. All modication rules are listed in testmethodology library. Continue the similar processes of each model as rst pass, except that15

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