Hello All. I am trying to understand modelling of phase noise in oscillators as done by the author of the following in the following link
https://ais.ku.edu.tr/AR/ALDEMIR2009...seEqnsTCAD.pdf
I understand that it requires Floquet Theory. Farkas's book 'Periodic Motions' describes it in good detail; however, it still is a little bit hard for me.

I wish to get a master's degree in math to independently understand papers of this sort.
Another paper that I am dying to understand is the following
http://petrified.ucsd.edu/~ispg-adm/...TSP_112007.pdf

I'd really really appreciate it if you can list the courses I should take to be able to understand the material in these papers. Thanks very much in advance.