I live in India, in a suburb in the national capital region. If you have ever visited us here, or have heard about the traffic in our city, you are sure to know that long drives in the city traffic are not fun. I am one of those drivers who likes the freedom to travel at my own time, in my own car, listening to my favorite music. BUT, I am definitely not one of those drivers who don't mind queuing up, bumper-to-bumper for hours every day! So, on my way back home, I need to make a decision — should I drive less, or more? Because, there are two different routes that I can take to home. The shorter route is usually busier at peak traffic times, has a lot of pedestrians, cyclists, and not everyone driving on that route is very sensitive to traffic laws. The other route, just seems so long. When I reach the crossroad, I almost get swayed in to take the shorter, seemingly straight path. The days I give in to that temptation, I usually reach home late . It can be the same when using software — what may seem to be a harmless shortcut could cost you a lot of troubleshooting time . Recently, one of our Virtuoso customers was taken aback when the physConfig they had copied using the unix Copy command did not reload the correct schematic. Why did they choose the unix Copy command over using the Virtuoso Copy Library option? Well, the unix Copy command was incomparably faster over the other! So, where could a layout circuit designer have gone wrong with using a simple Copy command? What could they have messed up with such a basic unix command? Actually, nothing. The only thing they probably needed to do was to not use the unix Copy command . Because, when you use the unix Copy command to copy a library, it is likely that the information in the physConfig view still references the original library cellview, not the new one. Deirdre Buchanan, Principal Software Engineer Virtuoso R&D , explains what can cause the issue, and what's your best bet to ensure a reliable copy of the library. When copying libraries or cells in Virtuoso that contain physConfig views, the only way to ensure your copied physConfig views are correct is to use the Tools — Library Manager — Edit — Copy command. And, don't forget to select Update Instances before you click OK on the Copy Library form. Selecting Update Instances ensures that the copied physConfig views are updated to have all the original library and cell name references point to the new library and cell names. If this is not done, it can lead to unexpected and hard to trace problems later. If you use an incorrectly copied physConfig view, your layout will be generated incorrectly. It will have connectivity issues. Let's look at a real-life scenario to see how a layout design can be impacted, if you have copied the physConfig view manually. When you launch Virtuoso Layout XL, the Configure Physical Hierarchy (CPH) utility elaborates the logical hierarchy, switching into physConfig view at the lower level. Let's say, CPH is elaborating an instance of symbol cph/nand2/symbol . Because you have manually copied the physConfig view, it is likely that CPH finds a physConfig view in the same cell as the symbol — cph/nand2/physConfig . Now, if this physConfig is incorrectly pointing to schematic cph/nand2_A/schematic instead of cph/nand2/schematic , CPH still elaborates into the incorrect schematic because that's the one it found the first. So, the layout that gets generated, will not be to your expectation. To ensure that the correct physConfig view gets used for layout generation, make sure you have copied the cells and libraries to be used for generation using the correct method — the Virtuoso Library Manager Copy option. Or, you may copy the library quickly, but might have to spend a lot of time fixing your layout! Related Resources Cadence Library Manager User Guide Configuring the Physical Hierarchy (CPH) cphCheckTopCellName For more information on Cadence circuit design products and services, visit www.cadence.com . About Virtuosity Virtuosity has been our most viewed and admired blog series for a long time that has brought to fore some lesser known, yet very useful software and documentation improvements, and also shed light on some exciting new offerings in Virtuoso. We are now expanding the scope of this series by broadcasting the voice of different bloggers and experts, who would continue to preserve the legacy of Virtuosity , and try to give new dimensions to it by covering topics across the length and breadth of Virtuoso, and a lot more…Click Subscribe to visit the Subscription box at the top of the page in which you can submit your email address to receive notifications about our latest Virtuosity posts. Happy Reading! Rishu Misri Jaggi (with inputs from Deirdre Buchanan)![]()
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