Hey, Ive got a problem with the npn transistors in the sky130 pdk... I am trying to build a Bicmos logic inverter... But I always run into a problem with the npn Transistors (the pnp just work fine...)

I have the same problem, so i guess there is an issue in the npn spice models. Will try to look at it. I haven't tested npn, and I don't know if its use is allowed in circuitry. (Cc @Tim Edwards)

It's a proper characterized device. There is some issue with the way the model names got handled in the PDK. It is a matter of having the right model/subcircuit name and the right include files, but I have not sorted out what needs to be fixed in the PDK to make it work without manual intervention.

@Tim Edwards the problem is that

sky130.lib.spice

includes (for example in the tt corner)

corners/tt.spice

, which in turn includes

../all.spice

which includes the npn transistors:

.include "../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__npn_05v5_W1p00L1p00.model.spice"

.include "../../libs.ref/sky130_fd_pr/spice/sky130_fd_pr__npn_05v5_W1p00L2p00.model.spice"

However these models are "cornerized", there is a

s

,

f

,

t

corner, so my suggestion is to include

sky130_fd_pr__npn_05v5__t.corner.spice

directly from corners/tt.spice and remove npn inclusion from

all.spice

. Same thing for the s and f corners. The

sky130_fd_pr__npn_05v5__t.corner.spice

defines some needed parameters before including the npn model:

.param
+ dkisnpn1x1=8.7913e-01 dkbfnpn1x1=9.8501e-01
+ dkisnpn1x2=9.0950e-01 dkbfnpn1x2=9.6759e-01
+ dkisnpnpolyhv=1.0 dkbfnpnpolyhv=1.0
.include "sky130_fd_pr__npn_05v5_W1p00L1p00.model.spice"
.include "sky130_fd_pr__npn_05v5_W1p00L2p00.model.spice"
.include "sky130_fd_pr__npn_11v0_W1p00L1p00.model.spice"

Not sure what is the best way to relate NPN

t, s, f

corners to cmos

tt, sf, fs, ff, ss

corners, may be there is no clear correlation of cmos corners vs bipolar corners...

Nice! Thanks!