Control voltage variation in PLL

[maharaja1989nellai]

Hi all,

iam finished my PLL inCP90nm.After locking my PLL the control voltage variation will be 6mV...After adding Decoupling capacitor(Decap=150p) between supply and ground the control voltage variation will be reduced to3.5mV...

my questions are
1) How much value of control voltage variation is best?
2) If i need control voltage variation about uV range what to do?
3) How much value of frequency variation is best?

 

[AdvaRes]

What is the best ?
It depends on your application requirements and your design budget.
To reduce variation you have to increase the capa of your filter.

 

[maharaja1989nellai]

i set my loop capacitor filter are within the Bandwidth limit(bandwidth=Reference frequency/10)...I need my PLL control variation will be uV range..


thanks

 

[AdvaRes]

I see,
So you have to use more sophisticated filters (higher order filter, active filter, etc)

 

[maharaja1989nellai]

thank you AdvaRes