Fractional N Vs Integer N Synthesizer?

[mesfet]

Hi All,

Wondering what are the differences between Fractional N Vs Integer N synthesizer? Are there any difference in designing the loop filter?


Thanks,
Mesfet+

 

[RFDave]

Fractional N Loop's allow you to have loop division ratios that are fractions. In other words, Fout/Fref=N.yyy

Awfully handy for decreasing the lock time. Loop filter design in mostly the same as an integer loop, but you generally can't use the starting point of LoopBW=Fref/10. THe problem is that you tend to get other sources of spurious, so you can't make the loop filter that wide.

Dave
www.keystoneradio.com