Hi I'm tring to calculate the jitter introduced by an ideal VCO driven by a noisy resistor (thermal noise).

from literature and theory I expect Phase noise:

            2*k*t*R*Kf^2                           |   where :     k -> bolthzman's
  L(f)=----------------------                       |                   t -> temperature [kelvin]
                    f^2                                   |                   R -> resistance
                                                                                Kf -> gain of the VCO

from this equation I get a result that match exactly with Cadence simulation done with Virtuoso SpectreRF v.5.1.41.

Virtuoso SpectreRF v.5.1.41 gave a new function in the pnoise tool: jitter noise type.

from the Ken Kundert's "Predicting the PN and J pf PLL frequency Synthesizers" and other papers in literature I expect a jitter:

        ____________        _______________
       |           f^2            |    2*k*t*Kf^2
J=   | L(f)* --------   =    |  ------------------
     \|            f0^3        \|        f0^2

My problem is that jitter prediction based on this theory doesn't macth with cadence result (completely wrong order of magnitude)
and I don't know why!!

the jitter's equation that I have used has benn taken from Ken's "predicting the phase noise and jitter of PLL-based frequency synthesizer" pgg.33, equation(80).

I don't understand how I can get the rms value: i belive (waching how the equation are obteined) that this expression is already rms.