< Tim Edwards> this file extracts to a 0 25 length mosfet bu open-source-silicon.dev #magic

<@U016EM8L91B> - this file extracts to a 0.25 leng...

Matt Venn

01/11/2024, 4:30 PM

@Tim Edwards - this file extracts to a 0.25 length mosfet, but the gate length is actually 0.15. Magic 8.3.331 extracts at 0.15, but Magic 8.3.413 extracts as 0.25.

Tim Edwards

01/11/2024, 5:12 PM

The gate length in my view is 0.24um, and I get a corresponding extraction:

Copy code

X0 drain gate source VSUBS sky130_fd_pr__nfet_01v8 ad=0.2405 pd=2.04 as=0.221 ps=1.98 w=0.65 l=0.24

No version of magic should extract this as either 0.15 or 0.25. How are you coming up with the "actual" measurement of 0.15?

Tim Edwards

01/11/2024, 6:59 PM

My suspicion is that the issue is that you are not consistently using

ext2spice

options, and what you are seeing is values for W and L that are not in microns, but which correspond to a

.option scale=

parameter at the top of the netlist that defines the relationship between listed dimensions and SI units. If you always use

ext2spice lvs

, that sets up a bunch of options including not scaling the values (other than that for SkyWater, the models have an implicit scale of 1e-6, so the units are microns, not meters).

Matt Venn

01/13/2024, 12:27 PM

Thanks Tim, I'll double check

Matt Venn

01/13/2024, 12:28 PM

The measurement came from selecting the gate and then typing box to get the dimensions

Tim Edwards

01/13/2024, 5:26 PM

That's not what I see, though.

Tim Edwards

01/13/2024, 5:28 PM

This is what you posted and what it looks like when I load it into magic:

Matt Venn

01/15/2024, 10:48 AM

ok, I'm confused, I probably didn't do ext2spice lvs and extracted the wrong dimensions

Matt Venn

01/15/2024, 10:48 AM

the box measurement I get is the same as yours

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