Does anyone know why magic puts the line

.option scale=5n

at the top of a paracitic extracted netlist for GF180mcu

Because you failed to start with

ext2spice lvs

which sets a bunch of "sane" parameters including ngspice format and no scale option. Always use

ext2spice lvs

first, and then if you are doing parasitic extraction, follow that up with

ext2spice cthresh 0

(or something bigger than zero) and

ext2spice extresist on

, which are the options that will get you (1) parasitic capacitance and (2) parasitic resistance (assuming you ran all the preparatory commands).

Ah ok thanks @Tim Edwards. This is what I have. does it look correct?

magic -rcfile $PROJECT_ROOT/ic/magicrc -noconsole -dnull << EOF
load $MAG_CELL
flatten ${CELL_NAME}_pex
load ${CELL_NAME}_pex
box values 0 0 0 0
extract all
ext2sim labels on
ext2sim
extresist tolerance 10
extresist
ext2spice lvs
ext2spice cthresh 0
ext2spice extresist on
ext2spice -o $OUTPUT_FILE_NAME
exit
EOF

Yes, that should work.

Thanks!