kicad-developers team mailing list archive

[pepijn de vos <pepijndevos@xxxxxxxxx>]

Hey all,

I'm a sw dev and recent IC design graduate, who made it his mission to
improve open source tools for IC designers.
To this end I've been playing with the recently released Sky130 PDK, which
is an open source PDK that does not require any annoying NDA's and will
actually allow sharing IC designs.

I've been looking at eeschema a bit as one of the options to do schematic
entry and simulation. However, I found that the integration with ngspice is
very limited at the moment. So I'm interested in making this better!

The first problem I ran into is that it can't plot the currents of a
transistor no matter what you add in terms of spice directives. More info:
https://forum.kicad.info/t/how-can-i-plot-transistor-currents-after-a-simulation/25324/8
So I have several questions.
Would this be a good first issue to tackle?
What would be the right solution?
Would anyone be available to help me in the right direction?

I think there are a few ways to go about it, which don't exclude each
other. One is to extend the logic that adds the currents for voltage
sources and resistors to also add transistors. Another is to update the
simulator UI to populate the signal list from the raw file, rather than its
own idea of which signals were saved, so that you can add custom .save
statements and plot them.

At the moment it is not clear that eeschema is a winning solution for
schematic entry for IC design, but if it turns out to be easy to extend for
this use case, and this aligns with the goals of the KiCad team, I would be
interested to further extend it.

For example, two other things that would be great to add is a way to plot
algebraic expressions of different signals, to plot things such as
impedance and transconductance, and a way to annotate operating points in
the schematic. But these are probably a lot more work, and also require
some more in-depth design discussion.

Regards,
Pepijn de Vos