Query about ADF4157 Sweeping Frequency

Hi, there

I have a question on ADF4157 when sweeping frequency. PLL output frequency band is 5.8GHz ~ 6GHz. Sweeping step is 1MHz or 2MHz with fPFD of 10MHz. When measuring the output of sweeping, there are glitches available at every 10MHz when sweeping. I attached the screenshot of DSO. then I tried to change fPFD to 20MHz. The glitches changed to every 20MHz accordingly.

Could you please analyze the problem? why are glitches available? how can I avoid the problem?

Thanks!

Best regards,

Wayne

testingresult.zip