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Simulators >> RF Simulators >> different NF results from "sp" and "noise" analysi
https://designers-guide.org/forum/YaBB.pl?num=1210838887

Message started by rf_man on May 15^th, 2008, 1:08am

Title: different NF results from "sp" and "noise" analysi
Post by rf_man 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?

Title: Re: different NF results from "sp" and "noise" ana
Post by didac on 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,

Title: Re: different NF results from "sp" and "noise" ana
Post by pancho_hideboo on 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.