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{{title|MTr/mm²}} | {{title|MTr/mm²}} | ||
'''MTr/mm²''' ('''mega-transistor per squared millimeter''') is a [[transistor density]] unit that serves as a [[figure of merit]] in quantifying a [[process node]]. The metric makes use of a weighted system consisting of two typical [[standard cells]] found in most [[standard cell library|libraries]] - a very small [[NAND2]] cell and a very large [[scan flip flop|SFF]] cell. | '''MTr/mm²''' ('''mega-transistor per squared millimeter''') is a [[transistor density]] unit that serves as a [[figure of merit]] in quantifying a [[process node]]. The metric makes use of a weighted system consisting of two typical [[standard cells]] found in most [[standard cell library|libraries]] - a very small [[NAND2]] cell and a very large [[scan flip flop|SFF]] cell. | ||
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== Overview == | == Overview == | ||
− | + | The metric was proposed by Mark Bohr, [[Intel]]'s director of process architecture and integration, in 2017. Bohr stated the metric is actually a resurrection of a similar metric that had been abandoned in the past. The metric attempts to take into account second-order design rules that the simpler density metrics such as [[CPP x MMP]] and [[CPP x MMP x Tracks]] cannot capture because they do not represent a typical [[standard cell]]. It should be noted that the metric explicitly excludes [[SRAM]] cell sizes because of the large variance in SRAM-to-logic ratio between popular chips. Furthermore, the metal pitch does not play a role in limiting SRAM as it does with other standard cells. Therefore, SRAM cell sizes should be reported separately alongside the MTr/mm² unit. | |
− | :[[ | + | Two [[standard cell|cells]] that are found in every [[standard library]] are used: a very small 2-input [[NAND]] cell consisting of just four [[transistors]] and a very large [[scan flip-flop]] cell. The NAND2 is weighted as 0.6 while the SFF is weighted as 0.4. |
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− | + | :<math>\text{Transistor Count/mm²} = 0.6 \times \frac{\text{NAND2 Tr Count}}{\text{NAND2 Cell Area}} + 0.4 \times \frac{\text{Scan Flip Flop Tr Count}}{\text{Scan Flip Flop Cell Area}}</math> | |
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:[[File:mtr-mm2.svg|800px]] | :[[File:mtr-mm2.svg|800px]] | ||
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== Example == | == Example == | ||
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== See also == | == See also == | ||
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* [[CPP x FP]] | * [[CPP x FP]] | ||
− | * [[CPP x | + | * [[CPP x MMP]] |
− | * [[CPP x | + | * [[CPP x MMP x Tracks]] |