PLL loop bandwidth?

when i design a PLL,i have a trouble about the loop bandwith,i don't how to choose its value.some articles tell (1/10)Fpfd,and some not,i am puzzled,can u tell me how to choose it?thank you very much...............................a puzzled guy

PLL loop BW of (1/10)Fpfd is a general rule.
The real loop BW should be calculated from the system analysis, taking into account switching time, phase noise, spurious, etc.

Then can u tell me the real loop BW calculated from the system analysis, taking into account switching time, phase noise, spurious, etc?some articles?Thank u .

RF system analysis it will tell you how much of each (switch time, phase noise, spurious, etc) you can allocate to the PLL.
For example very high spurious on the PLL side, could be attenuated by the following circuits and finally the system meet the spec.
Here is a document about loop filter design, but as I said you have to do your own system analysis and find the trade-offs:
http://www.am1.us/Papers/U11614%20PL...%20Fujitsu.pdf