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Diva and Conic Sides

djca

I'm using Diva for layout extraction and LVS. One class of devices I'm using is drawn as circles in the layout and the device parameter is determined by the area of the circle. When Diva performs the extraction and flattens the layout, the circles are converted to regular polygons with a certain number of sides. I simply measure the area of the circle to get the device parameter. I find that in most cases, the calculated area (after conversion to polygon) is smaller than the design area, because the number of conic sides used in the conversion to polygon is low. Is there a way to increase the number of conic sides used by Diva, so I can get my extracted value as close as possible to the design value? Thanks.

  • Diva defaults to using 24 sides to convert conics to polygons. This can be overriden on a per-shape basis. If you select the shape, and use the Edit Properties command in the layout editor, and then go to the "Properties" tab, you can add a new property called "STREAM SIDE COUNT" (note the spaces in the name, and it has to be in upper case), of type "int". If you set this to a larger number, it will use more sides in the resulting polygon. Note however that if the resulting polygon has more than 195 points, Diva will split it into multiple pieces in the output database (if saveDerived() is used in the rule deck, say). Internally though you can have a much larger number of points though. You probably don't want to go too high though...

    Regards,

    Andrew.

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