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Design >> RF Design >> Charge pump base fractional N PLL Design
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Message started by cmosa on Sep 6^th, 2017, 12:03pm

Title: Charge pump base fractional N PLL Design
Post by cmosa on Sep 6^th, 2017, 12:03pm

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