[time-nuts] tutorial on phase noise and PLLs?

John Miles john at miles.io
Thu Dec 4 18:45:56 EST 2014

> See how Fig 8 and Fig 9 provides two different cross-overs between the
> noise responces, and how the higher bandwidth doesn't have a "hump" just
> because the steered oscillators noise response get's sufficiently
> high-passed by the loop PLL as for the lower PLL it humps up because of
> them having comparable power (amplitudes yes, but their power adds, as
> it is noice).
> Maybe it is good enough for your purposes, but yes, I agree there should
> be a better presentation about the problem.

Another suggestion: fire up ADISimPLL and create a few different designs with various damping factors and combinations of VCO noise and loop BW.  It'll only take a few minutes, and the resulting plots will show both the individual and summed contributions of the different noise sources in a way that will instantly clue people in.  

-- john, KE5FX
Miles Design LLC

More information about the time-nuts mailing list