open-source-silicon.dev

I would like to export the simulation result in Xschem to text or .csv file for plotting. Any methods?

You can use ngspice `write` command.
for instance, `write filename.raw` will store simulation results in a .raw file that you can load and plot using xschem's `waveform reload launcher`.

If you want to load the data from an ngspice simulation into excel you can use the `wrdata` command, that will give you a text file that excel can easily parse.

Writing to a .raw file gives you a binary output.  Those can also be loaded in python if you prefer that for your plotting.  I've used this code in the past to read the data: <https://gist.github.com/snmishra/27dcc624b639c2626137>