[SOLVED] Simulate Vn to output jitter, pwm

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JanniS

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I made a PWM and a triangle generator to control it. I would like to see the phasenoise of the output signal.

I tried PSS + Pnoise, but i get an error saying:
ERROR (CMI-2208): `V4' is a periodic input signal, which is inconsistent with autonomous circuits.


V4 is a reset pulse with the same frequency as the PWM input triangle. I need it in order to simulate.

Another thing: I would like to add a noise source in series with the input signal, but I heard that PSS+Pnoise is based on transient signals, which do not include noise.

My question is: How can I simulate my PWM and see how noise, Vn, results in jitter (in seconds) at the output.

Thank you

Janni
 

Because the operation is not small-signal, traditional
noise analysis is likely unhelpful.

Your output jitter is likely to be dominated by things
other than intrinsic transistor / resistor noises. Even if
these devices have proper noise params for the transient
/ pnoise to work, they are trivial contributors relative to
input supply noise, ground bounce, PCB decoupling ringing,
intertrace and bondwire couplings.

Now if you can figure am input-referred noise amplitude
at the modulator input, the ramp slope will let you
transform that into a "time amplitude". I don't think I'd
bother with any more precise (as distinct from accurate)
simulation, given my experience above.
 
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