Thanks for the link Kai. Lots of general information that is usefull.

I am wondering if anybody has any experience with using Ferrite beads and EMI filters in a design? Items such as Panasonic EXC-CET103U(EMI) and EXC-CL4532U1(Ferrite).

I am not sure how to size one of these up for an application. Obviously the current rating should not be excedded but how are the frequency curves interrupted to be sure the correct part has been selected?

If the micro is operating at 2 MHZ does that mean the frequency curves of the Ferrite or EMI filter should be selected to have largested attentuation close to 2 MHZ range?

What about connecting analog and digital ground together at one point through a Ferrite. What are the frequency curves for that?