image.png

I guess it is not the full testbench. Everything is shorted.

@Rita The one on the left is a RF transistor. It has been characterized for high frequencies, but as such you are not allowed to change its dimensions or layout. If you look at the model you see W and L are fixed:

+ lmin = 1.75e-07 lmax = 1.85E-07 wmin = 5.045E-06 wmax = 5.055e-6

image.png

@Rita add command

remzerovec

before the write command:

.control
save all
dc vd 0 1.8 0.01 vg 0 1.8 0.2
remzerovec
write test_rf.raw
.endc

ok that works

@Rita The RF transistor should have specific values for Ad, As, Pd, Ps, ..., . If you just place the transistor and set W and L, xschem will use a simple formula to estimate these areas that contribute for parasitic effects. You should set these attributes to the actual value from the layout. Anyway I don't know how reliable these RF models are.

how do I get the area and stuff? there's no documentation on the RF devices

@Rita, if you have the original open_pdks cloned repository you can see the actual layout:

..../open_pdks/sources/sky130-pdk/libraries/sky130_fd_pr/latest/cells/rf_nfet_01v8_lvt/sky130_fd_pr__rf_nfet_01v8_lvt_bM02W5p00L0p18.svg

RF mosfets have double sided poly gate contacts to improve frequency response and dummy polys at the sides, presumably to reduce drain/source parasitics. However i don't know how to use these devices in the correct and accurate way. Don't know if you need to estimate Ad/As/Pd/Ps from the layout or just set these to 0. May be @yrrapt can help you.