pll vco control voltage issue

[sonnyasu]

vco control

hi I'm having a problem here with my control voltage to vco. after the loop filter, the control voltage looks like the plot in the attachment. Anyone knows what the problem is?

 

[biff44]

pll vco

What are you showing, an oscillosope trace, or some sort of simulation? What part do you not like about the trace?

 

[sonnyasu]

It's from the simulation. I think the spurs is not supposed to appear like that. Any idea?

 

[strennor]

the spur comes from the mismatch in your charge pump

4mV is not a big deal !

 

[sonnyasu]

Here is another screen shot of slow corner with cold temperature. The control voltage is on the top. Does this look normal? I thought the vco is out of range at the beginning but when I double check the vco frequency, it is in the range.

Added after 52 seconds:

here is the image