“A good neighbor increases the value of your property.” —Czech proverb Have you ever thought about the phrase, “safe as houses”? What could be safer than being curled up in your toasty warm house, under a blanket, listening to the wind and rain outside, drinking something warm and soothing, maybe watching old episodes of a show that you love ( koffOutlanderkoff ), while your kids are happily (hey I can dream) doing their homework in the other room… …until the power goes out. Suddenly, safe as houses doesn’t seem so safe anymore. The television flickers off, the kids get excited for the opportunity to use their flashlights, and the dust bunnies under the couch just might have evolved into creatures that are waiting to bite your toes. And don’t get me started about the combination of kids and candles. Time to pull out the board games (or, as my son calls them, “bored games”). Now, in this situation, the power outage might have been caused by a tree falling on a power pole or a transformer blowing or even a problem at the power station. It’s short-lived, and power is back in a day or two. But suppose you’re living in a neighborhood in which this happens a lot, even when there’s no storm involved. The power company may see that the power flickers off at your house a lot, and they can’t figure out why. Meanwhile, you happen to notice that your neighbor’s house is frequently lit like a carnival, and he boasts of his huge walk-in freezer where he stores his side of beef and three sides of pork and don’t worry about the coming apocalypse because he’s got you covered, and wait, is that a hydraulic press in his backyard? It’s times like these that one’s thoughts might turn to city planning and infrastructure allocation. Consider the following diagram. In my scenario, the resource in question is electricity and is flowing through the neighborhood following the red line. The neighbor lives in neighborhood H and you live in quadrant K. Your aggressive neighbor is hogging all the electricity, leaving you victim to blackouts and brownouts, so you can’t do the things that your house is designed to do, like run the washing machine to produce an output of clean laundry, or light the bedrooms so the kids can do their homework and get good grades and scholarships and go to college and get good jobs and support their moms in their old age. Little things like that. There are a few ways this “hotspot” problem can be addressed. The first is to move across town and make it someone else’s problem—but that’s not a solution, it’s just transferring the problem onto someone else. The three ways to really solve the problem are: Most obvious and easiest solution: move the aggressor to another neighborhood, maybe to a deserted neighborhood where there aren’t other people who need power? Voilà, no more brownouts. Another option is to have your aggressive neighbor attend a support group for electricity hogs that then inspires him to make vast changes in his lifestyle (but, you know, change is difficult). The most impractical solution is to bulldoze the entire neighborhood and start over, with an eye to making sure that your neighborhood aggressor has access to all the power (he thinks) he needs. Guess what? I’m making an analogy! I’ve been thinking about how the combination of the Voltus IC Power Integrity Solution and the Innovus Implementation System work together to do exactly what I’m talking about. Innovus builds the houses according to specifications and places them on the street; then Voltus performs analyses to single out the aggressors. The design of the neighborhood can then be fixed using the three solutions I listed above (sans support groups). Part of designing a chip is testing the flow of electricity through it. Each instance or “cell” in the design has a specific job in a specific neighborhood (or row) and requires a certain amount of power to do that job. If one block is designed poorly, or has a bug, or for some reason uses too much power (also known as “IR drop”; that is, the amount of power flowing into the component is significantly higher than the amount of power flowing out), the cell next to the power hog (also known as the “aggressor”) cannot work as specified, and have become “victims” to the aggressor. The areas affected by the aggressor are called “hotspots”. The Voltus IC Power Integrity Solution does that analysis. It analyzes the layout of the design and identifies the hotspots that are affecting the overall quality of the design, and answers the question of whether the design meets its original specifications. The IR drop and hotspots are annotated organically in a database, which can then be used in conjunction with the Innovus Implementation Solution to solve the hotspot problem. Within Innovus, a designer can use Voltus to perform the IR-drop analysis to find out where the large IR-drop is on the power grid line and then look at the instances (the houses) in that area (the hotspot). Voltus is the neighborhood watch captain who reports the aggressors. When the aggressor is singled out, Innovus looks at the local area and its surroundings, searching for places to relocate the power hog (the process is also known as “placement refinement”). Based on the Cadence secret real estate recipe, a new lot on another street is found for the aggressor’s house—that is, Innovus performs placement fixing based on the IR-drop analysis. The aggressor isn’t really a bad guy after all—he just needs more power to play his role of “meat-provider and hydraulic-press-owner” in the neighborhood. I bet he’ll even share some barbeque ribs with you at the next block party. After all the hotspots are identified and the aggressors are moved across town, Innovus calls on Voltus again for another round of IR-drop analysis to see if any hotspots remain. Typically, there are more adjustments to be made. But, as with all neighborhood planning committees, not all conflicts can be resolved. Sometimes the aggressor is so hooked into the infrastructure that he cannot be moved (or, as in IC design, an example could be a critical clock instance). If this happens, Cadence offers other means to address these problems.* Using Voltus and Innovus together, your circuits can be safe as houses—without using a bulldozer. —Meera PS. *Stay tuned for more about the concept of Cadence Full-Flow Digital tools!![]()
↧