I'm just recompiling ngspice with CFLAGS="-DXSPICE_EXP" to try supply ramping. I imagine there's a way to do this by controlling a voltage source with some ramp function - anyone can share something they use?

You can use a pulse voltage source with a long rise time for transient simulations.

thanks

I wasn't thinking about piecewise linear voltage sources, but they are simple also and can make your ramp.

that came from the bandgap demo you mentioned

I always use the

PWL

function on voltage sources.

@Matt Venn, this circuit: https://github.com/MastellaM/sky130_TAC3/blob/tatzelbranch/playground/test_OgueyAebischerBias.sch should do exactly what you have in mind … modulo possible installation, configuration, and version hells introduced by a "let's add another patch/python script on top instead of fixing the root cause" software engineering mindset, which forces you into an endless whack-a-mole game … There, I already fixed it (for me, that is) 2 months ago. This should work, with VDD ramping up from zero to 1.2 V in 100 milliseconds. https://github.com/tatzelbrumm/sky130_TAC3/blob/tatzelbranch/playground/test_OgueyAebischerBias.sch