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Measurements >> Phase Noise and Jitter Measurements >> jitter simulation with Virtuoso SpectreRF v.5.1.41
https://designers-guide.org/forum/YaBB.pl?num=1169808872

Message started by LucaV on Jan 26^th, 2007, 2:54am

Title: jitter simulation with Virtuoso SpectreRF v.5.1.41
Post by LucaV on Jan 26^th, 2007, 2:54am

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!!

Title: Re: jitter simulation with Virtuoso SpectreRF v.5.
Post by neoflash on Jan 26^th, 2007, 11:00pm

The equation on jitter, given there, is not rms jitter. It is spurious jitter i guess.

For calculating RMS jitter, you need to refer to Ken's document which is available on this forum.

Title: Re: jitter simulation with Virtuoso SpectreRF v.5.
Post by LucaV on Jan 29^th, 2007, 7:15am

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.