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

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Table 2.4: Types of block.TypesLogicMemoryCoreDetailed TypesData Path, Control, PLA, ILARAM, ROM, CAM, Register FileEmbedded coreTable 2.5: <strong>Test</strong> methodologies <strong>for</strong> each type of block.TypesLogicMemoryCore<strong>Test</strong> MethodologiesFull Scan, Partial Scan, BIST, Custom DFTScan, Memory BIST, Direct I/O access, Custom Array DFTScan, BIST, Direct I/O access, Custom DFT<strong>Test</strong> Methodology of Block (tm): Traditional testing methodologies <strong>for</strong> each type of functionalblock are listed in table 2.5.Gate Count of Block (g): Gate count represents the area quantity of functional blocks. It isexpressed as the number of two-input nand gates needed to ll up this amount ofarea. Its value depends on the functions of blocks, the algorithm, the implementationmethodologies, and the per<strong>for</strong>mance-area or the power-area trade o.Number of Nets in Block (n): The exact value of the number of nets in block depends ongate count and routing complexity. We oer an easy way to estimate this parameter:assume that the circuit consists of 2-input nand gates only, and is fanout free, then,each gate will connect to three nets and each net will connect two gates.estimation function can be derived asOurn = 3 g: (2.1)2I/Os of Block (p): General types of I/O include input, output and in-out. The complexityof interface circuits and the testability of block are aected not only by the numberof block I/Os but also by their types. In our study, we neglect the eect of dierentI/O types <strong>for</strong> simplicity.10

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