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different NF results from "sp" and "noise" analysi (Read 2604 times)

rf_man Junior Member Offline Posts: 28	different NF results from "sp" and "noise" analysi May 15^th, 2008, 1:08am different NF results obtained from "sp" and "noise" analysis of Spectre, the circuit is a LNA, the difference is about 0.2dB. setup as follows: sp: do noise= yes, mode= single ended noise: output noise = voltage input noise = port which one is more accurate? why the results are different?
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didac Senior Member Offline There's a million ways to see the things in life Posts: 247 manresa,spain	Re: different NF results from "sp" and "noise" ana Reply #1 - May 15^th, 2008, 2:10am Hi, Try to select in noise output noise:probe. If you don't select this option spectre takes into account the noise from the load and the results from sp and noise differs. Hope it helps,
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pancho_hideboo

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Re: different NF results from "sp" and "noise" ana
Reply #2 - May 15^th, 2008, 2:11am

rf_man wrote on May 15^th, 2008, 1:08am:

different NF results obtained from "sp" and "noise" analysis of Spectre, the circuit is a LNA, the difference is about 0.2dB.
setup as follows:
sp: do noise= yes, mode= single ended
noise: output noise = voltage
� �input noise = port
which one is more accurate? why the results are different?

In your setup, result of "sp" is correct as NF.

Why don't you specify "port" as "output noise" in "noise" analysis setup ?
Or if you set output port temperature as 0 Kelvin, you can get same NF from "noise-ana" as "sp-ana" even though you specify "voltage" as "output noise" in "noise" analysis setup.

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