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 ...

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12.07.2015 Views

DFT methodologies will be shown in the last section.2.1 NotationIn this section, we dene notation of the variables used in this paper. The variables aredesigned by the following two rules.Rule 1: A Capital letter represents a chip-level parameter and a small letter represents ablock-level one.For example: g is the gate count of a block and G is the gate count of a chip.Rule 2: Three parts compose a variable.A variable has the following basic form: Ts i , where the capital letter T , the smallletter s, and the subscript i represent the Type, the Stage, and the Item of theparameter, respectively. Examples of the notation are listed in Table 2.1. Sometimes,the stage can be implied by the item. For example, U wafer (cost per wafer) is obviouslyin manufacture stage, so we do not need to include this part in the notation. However,Cd mang(design management cost) must indicate the development stage explicitly,because management cost may occur during development and manufacturing stages.Table 2.2 lists some general types of parameters and their notation.Table 2.1: Examples of notation.Notation Type Stage Item DescriptionCd mang Cost Development Management Development management costTt f Time Test Final Final test timeU wafer Unit Cost Manufacturing Wafer Productive cost per waferTable 2.2: Type and notation of parameters in models.Notation Type ExampleC Cost Cd Development costR Ratio Rd mang Development management time ratioK User Dene Kd User dene development costT Time Td Development timeN Number Nv Volume to deliverU Unit Cost Ud eng Salary per design engineer8

2.2 Circuit DescriptionThis section denes parameters to specify circuit. Because DFT strategies must be appliedbefore detailed design, the circuit specication need to be targeted at the oor-planningstage. In this stage, designs are partitioned into several functional blocks, so we divide ourparameters into two groups: block parameters and chip parameters. As shown in Table 2.3,parameters with similar attribute are listed in the same row.The functional blocks can be IP cores from vender, previously designed blocks, or bareblocks designed from scratch.If this block is an IP core, the exact value of block mostparameters is available from the data sheet. As to redesign blocks, these parameters canbe estimated from previous designs. Unfortunately, if the block designed from scratch, theyneeds to be predicted by the block function, the block spec, and the user's experiences.Table 2.3: Parameters of circuit description.Block ParametersChip ParametersN B number of blocks in chipt type of blocka area of block A area of chipg number of gates in block G number of gates in chipgar gate area ratio of blockn number of nets in block N number of nets in chipnar net area ration of blockp number of I/Os of block P number of pinsA P pad area complexity of block , complexity ofchip re-usability ofblocktb testability of block TB testability ofchipv test length of block V test length of chiptm test methodologies used in block TM test methodologies used for whole chipThe subsequent discussions provide more details of each parameter:Type of Block (t): According to Sematech DFT workshop report [10], there are three typesof functional blocks: Logic, Memory, and Core. Each type needs dierent testingmethodologies. Moreover, each type contains some kinds of functional blocks. asshown in table 2.4.9

DFT methodologies will be shown in the last section.2.1 NotationIn this section, we dene notation of the variables used in this paper. The variables aredesigned by the following two rules.Rule 1: A Capital letter represents a chip-level parameter and a small letter represents ablock-level one.For example: g is the gate count of a block and G is the gate count of a chip.Rule 2: Three parts compose a variable.A variable has the following basic <strong>for</strong>m: Ts i , where the capital letter T , the smallletter s, and the subscript i represent the Type, the Stage, and the Item of theparameter, respectively. Examples of the notation are listed in Table 2.1. Sometimes,the stage can be implied by the item. For example, U wafer (cost per wafer) is obviouslyin manufacture stage, so we do not need to include this part in the notation. However,Cd mang(design management cost) must indicate the development stage explicitly,because management cost may occur during development and manufacturing stages.Table 2.2 lists some general types of parameters and their notation.Table 2.1: Examples of notation.Notation Type Stage Item DescriptionCd mang Cost Development Management Development management costTt f Time <strong>Test</strong> Final Final test timeU wafer Unit Cost Manufacturing Wafer Productive cost per waferTable 2.2: Type and notation of parameters in models.Notation Type ExampleC Cost Cd Development costR Ratio Rd mang Development management time ratioK User Dene Kd User dene development costT Time Td Development timeN Number Nv Volume to deliverU Unit Cost Ud eng Salary per design engineer8

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