Urgent - Noise parametres expressions

[nassim1]

noise parameter .s2p

Pls,

I need the different expressions to determine the 03 parameters of noise (Fmin, Rn and Gammaopt for LNA appllication since i have extrinsque parameters and S-parametres)...In reality, I have found many in diffentarticles as Gupta, pospiezazki and others but so difficult to understand and apply them .....

so pls, is there someone can help me ???

thx

 

[RF-OM]

It hard to understand what do you need. Usually noise parameters are inserted at the end of the S-parameters file (s2p or snp formats). If you use it with simulator program will do everything automatically.

Below is the part of the text that you may find on **broken link removed**

Noise parameters

It turns out that signal-to-noise ratio of a device is one of those "magic parameters" that are exactly described by circles of constant value on the Smith chart (much like small-signal gain). Contrast this with power amplifier responses such as contours of constant maximum efficiency, which are more generally described as "potatoes".

Once you have the noise parameters in hand using linear CAD software you can mathematically calculate the signal-to-noise response if the device sees impedances other than fifty ohms. Noise parameters are can be very accurate, if they are measured carefully.

There are three things that you are after when you measure noise parameters (four if you consider that gamma opt is a vector and has a real and imaginary part). Remember, the three noise parameters are functions of bias point, frequency and temperature, and of course, device geometry.

Gamma Opt
Gamma opt is the optimum impedance that must be presented to a low noise device to achieve its lowest possible noise figure.

Fmin
Fmin is the minimum noise figure of a device, and it is only achieved at gamma opt.

RN (equivalent noise resistance)
RN gives an indication of how fast the noise figure of a device degrades when it's input is matched to other impedances beside gamma opt. Lower RN is always desirable, it is a measure of the slope of noise figure versus impedance.

I hope it will help.
BR,
RF-OM

 

[nassim1]

Thx RF-OM,

I know that in S2p there are noise parameters but i have report to make which deals with using theoritical/amperical expressions to find the 03 parameters (Fmin, Rn and GammaOpt) after that i will compare them (results) with measurement given by datasheet. I want to tell you that i have model (Cgs, Rs...) its remaines only apply them to get the noise parameters....

Thank you

 

[mouloud08]

Hello,

I have understood wht you want to know. In reallity, it's not esay since there are many papers talk about noise and its parameters....
I do know if you have read these the attached articles, may will help you...

Mouloud

 

[mouloud08]

and .......

 

[RF-OM]

To nassim1,

Now I understood your problem. Did you check Gonsales' book? I am not sure I have it in e-form or not, but if you need this book I may check my library.

Best regards,
RF-OM

 

[nassim1]

Thx mouloud08 and thx RF-OM,

To RF-0M,

if about microwave transistor amplifiers analysis and design, i have it .... but no interesting things !!!!!!!!!!

I do know how can i use the expression since each one references to others where i have to chek them one by one and i do not have enough time ...

thx again

Nassim

 

[RF-OM]

Yes, I talked about this book about transistors amplifier. Unfortunately this is all what have to help.

Best regards,
RF-OM

 

[nassim1]

thx RF-0M for your kindly helping...

I do konw what i have to do but i will try with another way..

nas