I have been doing simulations of an analog block with diodes, but yesterday the simulations stopped working. I am now recieving the following error from ngspice:

option SCALE: Scale is set to 1e-06 for instance and model parameters

Warning: Model issue on line 2609 :

.model sky130_fd_pr__diode_pw2nd_05v5 d level=3.0 tlevc=1.0 area=1.0e+12 ...

unrecognized parameter (vb) - ignored

unrecognized parameter (gap1) - ignored

unrecognized parameter (gap2) - ignored

unrecognized parameter (xw) - ignored

Warning: No job (tran, ac, op etc.) defined:

run simulation not started

Any ideas what could cause this? Blocks without diodes are still working fine.

The messages about diodes are only warnings, I always get these, they won't abort the simulation. The error is the missing

tran

,

dc

op

,

ac

or whatever other analysis you need to do. Not really an error, but the simulator does not know what to do and exits. Check the testbench commands.

Yep, looks like I hadn't re-enabled my analysis. That would do it.

Unfortunately diodes (the simplest silicon devices IMHO) are poorly modelled, leading to inconsistent results and often different transient vs dc behavior. Do not trust much simulation data (expecially currents) for these devices.

Best to avoid diodes to the extent possible right?