VCO gain in Frac-N PLL system...

[gggould]

Hi all,

Does anyone know how to set Kvco properly in a fracN PLL system?
I understand the PVT/coarse tune/loop BW/spur parts, but is there anything else?

Say fref=10MHz with 111mesh DSM, does the Kvco need to be larger than 70MHz?? Please add any parameter if I missed.

Thanks
gggould

 

[soroosh_moallemi]

Pay attention that it is not suitable to increase the value of the Kvco. Because it leads make your PLL unstable. try to design your VCO with Kvco as low as possible.
have fun