Hi, when doing lvs on klayout, schematic netlist W and L are measured on megameters (10^6). This happens because schematics dimentions are measured on micro scale, so W and L don't need the

u

. Klayout is not aware of this context. When setting

.option scale 1

on ngspice so

u

is required in schematics, the simulations breaks so it is not a solution. I think that klayout should have a parameter to change the way it interpretates the sizing of schematic netlist, since layout netlist is fine.

Unfortunately the

.option scale

is set inside the SkyWater model files and applies to all the model equations, making it extremely difficult to pull out of the models, as much as I would like to. Since SPICE does not recognize the ordering of components, any

.option scale

you use in your own schematic will just be in conflict with the one in the models. ngspice does not complain about the conflict and seems to just ignore the one in the schematic netlist.

Thanks Tim for the explanation. That's unfortunate but at least we have magic extraction and netgen lvs working fine with layouts designed in klayout. Is klayout support enough to design or we should only use magic? Ignoring the fact that the drc rules are limited to "manufacturing rules" only

I think that designing in klayout is fine, if that's what you're most comfortable with.