Noise on 3.3V - LM22670

Hello to All

I am using Switching regulator - LM22670-ADJ  3.3V

Power my board Digital and Analog Side.

The for the analog side the 3.3V is filter with ferrite bead 1kOhm@100MHz and decoupling  capacitors.

I am measuring some analog sensor  - and my ADC  got very noisy signal  and we cannot work with that signal.

On the scope I saw that I have about 200mV ptp noise in the Vout of the switcher (the prob was with minimum length - avoid antennas, GND surrounding the prob)

When I am zoom in the 200mV I saw a signal  ~91MHz (maybe there is more signals but non seen for that stage - my scope Agilent MSO-X2024A  200MHz)

When I test my switching SW pin  I found that there is a ringing (rising up & falling down) with that frequency - ~90MHz.

My layout is as minimal as possible - 2 side of the board  -- like the EVB - I can post SCH and layout if needed

I saw few TI  tutorial  - using  NP0 C0G  capacitors with high SRF and using RC snubber circuit on Vout

http://e2e.ti.com/support/power_management/simple_switcher/w/simple_switcher_wiki/2243.understanding-measuring-and-reducing-output-voltage-ripple.aspx

http://trainingcenter.ti.com/ti/training/cplayer?2&umfid=a4e91a82-46df-46d2-ab02-3e553f53d3d6

with no Formulas  how to find capacitors values

or for  snubber circuit

http://www.ti.com/ww/en/analog/power_management/snubber_circuit_design.html

with few unknown that cannot use the Formulas  

My problem is how calculate the values on the capacitors or the snubber circuit to filter out the noise freaquency

Could any body give good example for such problem with detailed solution

Your help needed

Regards,

Mayer