fluctuations in pll phase noise profile

[fenfei]

I designed a PLL frequency syn, fractional N PLL.But I found that there were fluctuations in pll phase noise profile.meanwhile,there were spurs sweeping from -500kHz to +500kHz offset when fluctuation accoured.
Anyone has met the problem?

 

[biff44]

around every 4 months someone posts a similar non-descript pll question on the RF & Microwave board. You should search there for the answers.

 

[fenfei]

around every 4 months someone posts a similar non-descript pll question on the RF & Microwave board. You should search there for the answers.

Thanks for your reply.I can't find the post,could you give me a link?

 

[hhq414]

Thanks for your reply.I can't find the post,could you give me a link?

Is anyone know the possible reason?