Vicente Osorio

03/09/2023, 6:16 PM
Dear @Tim Edwards I've been extracting netlists from layouts in MAGIC through a command line in Jupyter Notebook. Nonetheless, something is happening in between when I execute the command line
PDKPATH="${PDK_ROOT}/sky130A" magic -dnull -noconsole mag_files/waffles_nmos.tcl
. I get different parasitics when I execute it in Jupyter or in the main Linux terminal. I don't know the cause of the problem, as I only change the place I'm accessing the terminal. I suppose it may be something to do with the kernel. I hope you can help me understand what is going on. Best regards, Vicente Osorio Rivas

Tim Edwards

03/09/2023, 6:41 PM
Most likely it has to do with the version of Magic. The parasitic capacitance modeling was updated relatively recently. I occasionally update the parasitic coefficients in open_pdks, but I have not done so for SkyWater recently, so I suspect the differences come from the version of magic being used.
There was, however, a very recent change in the PDK where some contact types were missing from a list and so their resistances were not contributing to the parasitics. I doubt that's what you're seeing, though.