Andrew Beckett
Senior Fellow
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Life, don't talk to me about Life...
Posts: 1742
Bracknell, UK
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Well, noise figure is defined as the ratio of signal-to-noise at the input to signal-to-noise at the output. The output would not be a problem if it was not terminated with a port, because all that happens is that the noise gets excluded from the load anyway. But the input is an issue - you need to have a noisy source at the input, which is what a port gives you (because of the resistor in the port). So I'm not convinced noise figure is a useful metric in a voltage-based system.
Conversion gain is straightforward, because you are just plotting voltage gain instead of power gain.
For compression point, I wrote a solution on this on sourcelink.cadence.com - number 11025262 - a while back. For this I used a vcvs and a port to transform dBV into dBm (effectively) and allow a port to be probed for measuring the output "power". The input sweep was a voltage source with the amplitude set to 10**(dbvrf/20) and you then sweep dbvrf. However, I think you could achieve the same thing by sweeping the voltage source the same way, but using the Net (dB, 1 ohm reference) choice for the Select field on the direct plot form. So no need to do the messing around with vcvs...
Regards,
Andrew.
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