Ken Kundert
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Hmmm. Okay, I am starting to see some of the subtlety. The simplest model for flicker noise is a stationary noise voltage in the gate, so I think of it that way, but the simulator does not actually put a voltage source in the gate because that would require extra nodes, which would make the simulation more expensive. However, the simulator can still compute the transfer function from the gate if it wanted to by dividing through by gm, but it seems like SpectreRF is not doing that. If it were, then the units should be V/V rather than V/A.
Having said that, the units given in your screen capture are very confusing to me. What is the meaning of :sqrt(Hz). A transfer function is not a noise and so should the units should not include :sqrt(Hz). I also do not know how to interpret the colon.
Now, as to your question as to why the transfer function for channel noise and flicker noise are different, I cannot say. You might ask Cadence about that.
Also, if the gm term is not being included in the flicker noise transfer function, then it does seem as if the PXF and PNoise transfer functions should be exactly the same. I cannot explain why they would be different. Perhaps there is something in the documentation that describes it. After all, there must be some reason why they provide PNoise separations as opposed to just advising you to use PXF.
-Ken
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