Ripple Filter Damping Techniques

Found this very useful article by Kevin M. Tompsett on damping of a PSU output filter:

http://www.analog.com/media/en/technical-documentation/technical-articles/Designing-Second-Stage-Output-Filters-for-Swit… 

In Fig 4 there are 3 techniques shown to damp oscillation in the output C-L-C pi filter:

1. Resistor across the inductor

2. RC load on input

3. RC load on output

I can understand how techniques no. 1 & 3 work as they are loading the output of the filter to damp the oscillation, but I do not understand how no. 2 works. How can a RC load on the input of the filter stop oscillations on the output? It seems to me that the output LC can still resonate.

Any clarification of how technique no. 2 works would be well appreciated!

Thanks, Ken

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