Noise at Buck regulator

[dunv]

After taped out,I found about 100M Hz noise apperaed at the PWM signal of my BUCK regulator .Ilet the PWM signal output pin to be floating,disconnected it with any external compnents,but It still be detected. I think maybe it is caused by the parasitic inductor and capacitor,or by the worse phase margin? Expected somebody give some suggestions.
Thank you very much

 

[tsanlee]

Can you open loop your regulator(FB>Vref,switch off ) ,we can cehck the internal circuit .

100MHz Noise maybe come from internal Ramp Oscillator or Gate Driver or MOSFET.

The IC layout and PCB layout is so important in power IC system.

You can check these item .

 

[yeewong_su]

Try to filter the noise using the exe cap.