Is there a method of inserting dummy devices? I saw in an earlier message that you could add them into the schematic and use a command "ignore shorted devices" but the command doesn't seem to work.

I usually just draw the dummy devices into the schematic and layout and they get included into the LVS. It's a bit tedious to add them to the schematic, but it works. It seems like what you want is to not add the dummy devices to the schematic but to let netgen deal with the dummy devices in the layout by ignoring them. I don't use the

ignore shorted

command in netgen, although I wrote it, and it presumably works in some sense. The actual command is not

ignore shorted devices

but

ignore shorted <device>

where

<device>

is a valid device name such as you would find in the

sk130A_setup.tcl

file. You would probably want to copy that file and add entries for each device type for which you have dummies; e.g.,

ignore shorted "-circuit1 sky130_fd_pr__nfet_01v8"

. Note that the netgen command was just dropped in once to support an immediate need and has not been properly developed. The only thing it is checking is subcircuit types, and it only considers them to be "shorted" if all ports are shorted together, while there are numerous ways to connect a device and it still operates as a "dummy" device. There are better ways to deal with shorted devices in netgen, but I would need to work on an implementation.

Sorry, I just wanted to double check. Assuming I have several devices shorted on the layout but no extra devices defined on the schematic, I can technically get LVS to ignore those shorted devices on the layout with

ignore shorted "-circuit1 sky130_fd_pr__nfet_01v8"

? Furthermore, what would the full LVS command be?

lvs "circuit_schematic.spice circuit" "circuit_layout.spice circuit" sky130B_setup.tcl ignore shorted "-circuit sky130_fd_pr__nfet_01v8"

?

@Jason Xie: As mentioned above, the restriction is that dummy devices are only ignored if all ports of the device are shorted together. The command would require that you create a copy of

sky130B_setup.tcl

, edit it, and add the

ignore shorted

command.

Awesome, that worked. Thanks! Sorry, I must have misread your first message.