I have following questions related to design and modeling of fractional-N sigma Delta (second order, MASH 1-1) PLL. It is a basic charge pump based type II third order PLL.
1. For Fref=26MHz, PLL BW(fc)=1MHz, fc >=5 fz and fp >= 5fc, fractional value of 0.46154, Will there be noticeable fractional spur at 2MHz ?
2. Can modeling approach described by Michel Parrot et. al. (JSSCC 2002) model/estimate fractional spur level?
http://ieeexplore.ieee.org/abstract/document/1020242/3. Any recent work on estimating fractional spur where Fref/fc is less than 25?
Thanks
-Potential Currentvala