Hi all,
I am trying to do some noise simulation in Cadence.In that i put an input port,and select the output for noise .The simulator gives output referred noise but not input referred noise.How to get the input referred noise?????
By the awy i have heard some term like transient noise simulation,what is that??

manodipan wrote on Oct 1^st, 2008, 2:16am:


Spice's "noise" is a small-signal analysis, like ac: the circuit is linearized about an operating point to compute the transfer function from the noise generators to the output.

PNoise goes a step further and computes a "time-varying operating point" but again linearizes the circuit.  Similar for HBnoise.

Transient noise does a regular transient analysis, but then uses the noise equations to inject random amounts of charge (or voltage) and attempts to compute the full nonlinear response in the presence of noise.  I think there's a whitepaper on SourceLink.  It's really the only way to get the noise performance of sigma-delta converters (and other circuits that aren't periodic nor linear).  But it's tricky to not lose the noise in the numerical roundoff of finite-precision computer arithmetic, and to have good convergence in the presence of the random noise.

Cadence has a whitepaper on transient noise available on SourceLink; you should read it to understand the assumptions and limitations.

It's a transient analysis, as I said before; the noise is injected at each timepoint during the analysis.

Hi Frank,
can you attach the pdf,because i have to register to source link and i dont know the hostid of our license server..thanks a lot..