Hello, I was facing some lvs issues regarding mismatch in number of devices in a custom analog block...

Soumil Jain

05/20/2022, 7:32 PM

Hello, I was facing some lvs issues regarding mismatch in number of devices in a custom analog block. I used multiple fingers for nmos and pmos transistors, but netgen does not seem to merge the devices correctly, specifically in the netlist generated from magic layout. Could it be be due to permute in source and drain of transistors not happening properly?

col_driver_1x2_magic.spice comp.out col_driver_1x2_xschem.spice

Mitch Bailey

05/20/2022, 10:59 PM

Could you post the command you use to run netgen lvs?

Mitch Bailey

05/20/2022, 11:05 PM

And the command you use to extract the layout. Your extracted top subcircuit is strange

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.subckt x/Volumes/export/isn/soumil/ReRAM_sky130_files/col_driver_1x2

Your top xschem subckt is commented out, too.

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**.subckt col_driver_1x2

Soumil Jain

05/20/2022, 11:07 PM

for netgen I use “netgen -batch lvs col_driver_1x2_magic.spice col_driver_1x2_xschem.spice”

Soumil Jain

05/20/2022, 11:08 PM

for extracting layout it’s “extract all ext2spice hierarchy on ext2spice scale off ext2spice”

Soumil Jain

05/20/2022, 11:09 PM

the path for sub circuit ideally is /Volumes/… ideally, not sure what to the x is

Mitch Bailey

05/20/2022, 11:19 PM

For extraction, can you add

ext2spice lvs

like this

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extract all
ext2spice hierarchy on
ext2spice scale off
ext2spice lvs
ext2spice

For lvs, you'll need the setup file for mos source/drain permutability. This also requires a top level subckt named

col_driver_1x2

in both netlists.

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netgen -batch lvs "col_driver_1x2_magic.spice col_driver_1x2" "col_driver_1x2_xschem.spice col_driver_1x2" $PDK_ROOT/sky130A/libs.tech/netgen/sky130A_setup.tcl

✅ 1

Mitch Bailey

05/20/2022, 11:23 PM

Also https://skywater-pdk.slack.com/archives/C017P3RAD42/p1652683006486549

Soumil Jain

05/21/2022, 3:15 AM

Thanks @Mitch Bailey, I attached the spice files from those commands. The magic netlist however does not have the top level subckt named 'col_driver_1x2'. The netgen command complains about that so I tried -

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netgen -batch lvs col_driver_1x2_magic.spice col_driver_1x2_xschem.spice $PDK_ROOT/sky130B/libs.tech/netgen/sky130B_setup.tcl

which gives property errors (as, ad, ps, .. not present in magic netlist). Also I was using sky130B.

error_log.txt col_driver_1x2_magic.spice col_driver_1x2_xschem.spice comp.out

Mitch Bailey

05/21/2022, 5:02 AM

I don't know why your layout top cell is being extracted as

x/Volumes/export/isn/soumil/ReRAM_sky130_files/col_driver_1x2

but try this

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netgen -batch lvs "col_driver_1x2_magic.spice x/Volumes/export/isn/soumil/ReRAM_sky130_files/col_driver_1x2" "col_driver_1x2_xschem.spice col_driver_1x2" $PDK_ROOT/sky130B/libs.tech/netgen/sky130B_setup.tcl

✅ 1

Soumil Jain

05/21/2022, 5:37 PM

ok that worked! Thank you still unsure why the top cell is being extracted that way.

🎉 1

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