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Design >> Analog Design >> Noise Figure based on rmsnoise
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Message started by ezencir on Sep 27^th, 2006, 9:52am

Title: Noise Figure based on rmsnoise
Post by ezencir on Sep 27^th, 2006, 9:52am

Hello All,

NF equation says
NF=10*log10(Vn,out**2/(A**2*4kTRs)) where A is the voltage gain from source to output, and Rs is the source impedance.

How can I get Vn,out**2 term from rmsNoise function of Cadence?

In other words, what is the exact Analog Design Environment output expression to calculate NF?

Thanks for the feedback.

Title: Re: Noise Figure based on rmsnoise
Post by ACWWong on Sep 27^th, 2006, 11:53am

you should use the "add to outputs button" to get the expression under the results->direct plot-> main form of the ADE GUI.
So output squared rms noise is:
getData("out" ?result "noise")**2
likewise the noise figure is:
getData("NF" ?result "noise")

the use of the rmsNoise funtion integrated the noise over a certain bandwidth. Normally one plots NF(f) using Av(f) and vn(f) so the rmsNoise calculator function might not be that useful.