RMS phase jitter, not sure the right formula
Below 10KHz, the PLL noise floor is controlling the phasenoise, which will be assumed to be some ratio of the XTAL reference.

And if you view the phasenoise as the PhaseModulation component (the quadrature energy) of random noise summed with a pure sinusoid, then phasenoise bandwidth will either be sidebands of modulation, or will be additive random noise in some bandlimited positive-feedback system. If there is a 2nd harmonic, then that can sustain sidebands as well.

Hope this helps. Its a good question.