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#analog-design
Title
# analog-design
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Nikhil Poole

05/28/2021, 8:10 PM
I'm running into more property errors with netgen which I can't explain and which appear to be as simple as swapping transistors. I'm also confused though because the comp.out file refers to the exact same two devices twice (M27 in the schematic and M40 in the layout) but extracts different lengths in the two error lines. I've double-checked both the layout and schematic files and it should be able to match the two dummy devices: one of the dummy devices has length 1um and the other has length 4um. I've attached the comp.out file and the two netlist files in the comments.
comp.out,pfd_cp_lpf_lvs_layout.spice,pfd_cp_lpf_lvs.spice
Note: the other dummy device that it should be able to swap with is M29 in the schematic and X98 in the layout.
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Tim Edwards

05/28/2021, 8:46 PM
It looks exactly like the situation that I corrected in a previous commit to netgen, so I must have missed something.
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Nikhil Poole

05/28/2021, 8:56 PM
Yeah, I had already pulled your previous commit, so this must be something else.
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Tim Edwards

05/28/2021, 9:06 PM
It's similar, but before I was specifically solving for the case of capacitors, which are set up a bit differently because you can't add widths together like transistors. So it looks like something I did for sorting property values for capacitors ended up breaking the sorting for property values of transistors.
Yeah, looks like I managed to screw up the transistor width sorting; it's sorting on M instead of width because of something I did to make the capacitors work. It should be a simple fix, and I should have it done a little later today.
Okay, I reworked the order in which netgen sorts properties, and it should now be back to sorting transistors and resistors correctly while also handling capacitors. An update of netgen from opencircuitdesign.com should get you a clean LVS again.
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Nikhil Poole

05/29/2021, 1:27 AM
Awesome thanks!
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Tim Edwards

05/29/2021, 1:28 AM
Well, sorry about the mess I made of that previous update. It's no fun spending time trying to figure out what's wrong with your circuit only to finally decide it's the tool that's screwing up.
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Nikhil Poole

05/29/2021, 1:29 AM
No problem, I really appreciate your responsiveness to these issues.
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Tim Edwards

05/29/2021, 1:30 AM
I know you're under a tight deadline. : )
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