基础版图技术毕业论文中英文资料外文翻译文献.doc

基础版图技术毕业论文 中英文资料外文翻译文献7外文资料原文外文资料原文IC Mask Design：Essential Layout TechniquesChristopher Saint and Judy SaintCommon Sense Noise SolutionsLets go through each one of our real word rock band solution, one at a time. We will see how they map across to mask design techniqueswhat we can do in both the design world and the layout world to achieve some of these noise reductions.Turn Down the volumeOur first request was to ask the rock band to turn down their music. Turning down the volume would be like reducing the signal swing in a circuit. In layout there is not a lot we can do to reduce the signal swing.By signal swing I mean the amplitude or value of the voltage that is being wired around the chip. In a digital circuit, for instance, the zero state is represented by 0 volts, whereas the one state can be represented by 5 volts. This is a voltage swing of 5 volts.Now, if we were to reduce that voltage swing to only 2 volts, then we would be switching less energy each time a flip-flop flips. Or flops. That is the direct equivalent of turning the noise generator down, turning the volume down.As we mentioned in the opening thoughts to this chapter, mainly the digital part of a mixed signal chip is the section that needs to be quieted. So, if you can get a digital logic family that is inherently quiet, i.e., that has very small voltage swings, then that helps keep the overall noise down from the start.Voltage swing is not primarily a layout issue, but is can be, to a certain point. Suppose your circuit designers come along and say they have a chip for you to layout, with a reasonably high chunk of digital circuitry. They have indicated that they plan to use this certain library, which you know is a 5-volt swing library. You remember that you used a digital library on a similar chip some time back that had a 2-volt logic swing.You can turn around and say, “Well, are we worried about noise? Because there is this 2-volt swing library that could do the kinds of things you want. That might help.”And they might agree. The amount of voltage swing is mainly a circuit designers decision, but a good mask designer knows the options and when to suggest them.Rock Band Moves Inside Their HouseThe second item we talked about was asking the rock band to go inside their house. The house provided some isolation, some sound insulation. The sound had to get through the walls of the house before it got to our ears. Now, this is something we can definitely devise in layout.We can effectively hide a noise-generating block behind a Wall of Death, as I call it. Its a Wall of Death because it stops anything trying to get past. We mentioned this earlier.Figure 6-1 Put the noise inside a little houseSo, you make a wall. You make all the noisy circuitry go inside its own little house.There are various layout techniques to make that wall. How you build your wall depends on who you are, what process you have, and what test chips have been made. The method is variable, but one easy way is to wrap a big ring of ground substrate contacts around the whole block. Remember, noise travels through substrate very easily.As the noise tries to escape the block through the substrate, it first encounters a ground substrate contact. Hopefully, any noise voltages or noise currents will be attracted to this contact since it is grounded.Figure 6-2 Placing some slippery exits in the way help eliminate traveling noiseIf we were to have a very small substrate contact as our ring, noise could work its way around or underneath it. A big contact means the noise cant get through. So make it a decent size.Go Inside Your Own HouseWe have already placed guard bands around our noisy block. Now, not only might you guard band your noisy block, but if you have a quiet block somewhere in your circuit, you could guard band both of them. Its like walking into your own house as well as the band walking into theirs. Twice the isolation.Figure 6-5 Maybe both blocks should go inside their little housesClose All WindowsPutting a solid guard band around the whole noisy block is effectively like putting the noise generating circuitry inside the house with all the windows closed.If you have any gaps in the guard band, its like having some windows open. Some nose can leak out. And believe me, a tiny opening in just one window can let a lot of noise escape. Keep the guard bands closed.Move to a New NeighborhoodNext lets look at the concept of moving to a new neighborhood in our rock band example. This option is directly a mask designers technique.Here we have two floorplans of the same chip.(See Figure 6-7.) Our initial floorplan on the left shows the quiet stuff and the noisy stuff placed next door to each other. But, if you can, why not have the quiet and the noisy stuff as far away from each other as you possibly can, as in the floorplan on the right?Figure 6-7 “Hey, buddy, do you know how to sing Far Far Away?”This placement technique should become daily habit for good mask designers. With time, you just know to automatically place noisy and quiet circuits away from each other, without thinking about it.翻译文稿翻译文稿集成电路掩模设计：基础版图技术Christopher Saint and Judy Saint利用常识解决噪声的方法让我们从头至尾一个一个地看看我们真切的解决摇滚乐队的方法。我们将看到它们如何可对照用于掩模设计技术我们在设计领域和版图领域可采取哪些措施来减少这些噪声。调小音量我们的第一个要求是请摇滚乐队小声一点。调小音量在电路中相当于减小信号的摆幅。在版图中我们用来减小信号摆幅的办法不多。信号摆幅即指导线在芯片各处的电压振幅或电压值。例如，在一个数字电路中，0状态由0伏来代表，而1状态则由5伏表示。这个电压摆幅就是5伏。现在如果我们想把这个电压摆幅降低为2伏，就必须在触发器每次触发时切换较少的能量。这相当于直接关小噪声发生器，即调小音量。正如我们在本章的引言中提及的，在一个混合信号芯片中主要是要让数字部分保持安静。所以，如果你能采用本质上比较安静的数字逻辑系列，即它有很小的电压摆幅，那么从一开始就能使整个噪声较低。电压摆幅基本上不属于版图问题，但在某些时候也可以成为版图问题。假设你的电路设计者过来说，他们有一个含有较多数字电路的芯片要你画版图。他们指出他们打算采用某一标准库，你知道这个库德电压摆幅是5伏，你记得过去曾在一个类似的芯片上用过一个2伏逻辑摆幅的标准库。你可以婉转地说：“好吧，我们是担心噪声问题吗？我记得有一个2伏摆幅的库可以达到你所希望的目的。它也许会更好些。”他们可能会表示同意。电压摆幅的大小主要由电路设计者来决定，但一个好的掩模设计者了解可以有些什么选择并且知道应当在什么时候建议使用它们。摇滚乐队搬进他们自己的屋里我们提到的第二个办法是请摇滚乐队搬进他们的屋里。这个房子提供一些隔离，即隔音。声音要穿过房屋的墙壁才能到达我们的耳朵。这也是我们肯定要在版图中策划的东西。你可以把产生噪声的模块有效地藏在被我称之为“死亡之墙”的后面。之所以称为死亡之墙是因为它阻挡了任何企图穿过它的东西。我们在前面曾提到过。所以，你建了一堵墙，并把所有的噪声电路都放进它们自己的小屋里。图 6-1 把噪声屏蔽在一个小屋里建立墙壁的版图技术有许多种。如何来建立这些墙取决于你本人，取决于你采用的是什么工艺和已经做过的测试芯片。方法多种多样，但有一个简单的方法是用一