Originally posted in cdnusers.org by julian2007
suppose I have a circuit, and I do three simulations as described below
1) add a port as input probe, set its resistance, say 50 , and run
noise analysis, now I can get input referred noise voltage from the
result, call it NP.
2) replace the port with a voltage source in series with a 50Ohms
resistor, run noise analysis, get the input referred noise voltage
,call it NV.
3) replace the voltage and series resistor with a current source
in parallel with a 50Ohms resistor, run noise analysis, get the input
referred noise current, call it NI.
Now can any one tell me what's the relationship btw these three quantities.