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Layout scaling and inconsistent shape dimensions issue.

JS20250120924

Hi everyone,

I recently encountered a perplexing issue while scaling up my layout. Could you please take a look?

Virtuoso version: IC23.1-64b.ISR12.37

I currently have a GDS file that I need to scale up by a factor of 1.11. I achieved this by adjusting the design scale factor within Xstream to enlarge the layout design.

However, I encountered an issue with inconsistent shape dimensions. For instance, my original shapes were sized at 0.5, but after scaling up, most appear as 0.556 while a small portion show as 0.555.

Can this be resolved through certain settings, or do I need a SKILL script to handle this issue?

  • Andrew Beckett

    I suspect the most likely scenario where things are ending up at 0.556 width is if they were paths or pathSegs to start off with, and your database has a DBUPerUU of 1000 (i.e. a database resolution of 1nm). Paths and pathSegs need to have a width which is an even number of database units, and so you cannot have 0.555 as the width. For other polygons and rectangles, it's the points themselves that are scaled not the width, but I would expect the rounding error to truncate in the same direction, but I'm not sure without doing an experiment (maybe if the shapes are centred around the 0 x or y coordinate then they might round in different directions to get onto the database grid). Without seeing some example data, it's hard to be sure...

    Andrew

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