Hi guys,

Do you know what kind of noise happens in my circuit the graph shows the output of my buck converter (https://my.mouser.com/ProductDetail/Murata-Power-Solutions/NCS6D1212C?qs=%2BCWUF9yEAmkY/EA6uE7d/A==) even added the filter circuit still happens noise output


Zoom in picture




Before zoom in

 

Where it was measured? Is it output with AC coupling? What is the time scale of the first waveform? The bottom waveform shows peak-to-peak >2V. That doesn't look related to the first one. Check your ground connection of the probe: when ground is loose you would see something like this. Also time scale of 5ns is not very useful: you need to check closer to switching frequency of the converter. Also check that you are not measuring noise in the ground fly lead of the probe: connect the alligator to ground of converter and touch it with probe tip. You may still see some noise just make sure it looks much smaller than what you are measuring. If it is the same - means you are measuring noise induced into ground loop

 

Did you meet the required minimum load from the datasheet, i.e. 10% of full load?