@User @User: LIP6 has a static timing analyser that can also be used to generate liberty files for cells and macro blocks: https://www-soc.lip6.fr/en/team-cian/softwares/tasyagle/. They simplified transistor models for digital timing simulation so it should be faster than ngspice. The public downloadable version is currently not under an OS compliant license but LIP6 will relicense it under GPL. They did not find the time yet to do the License change in the source code.