Noise figure

spanika kamuni

Other Parts Discussed in Thread: TINA-TI

I have a schematic as follows. i want to find the noise figure of my schematic without any input given. But since TINA demands atleast one input I have just put in some ac source as my input.

now when i make noise analysis i get some graphs but i really do not know how to use these graphs to calculate the noise figure. also I am not clear with the SNR graph. noise factor is SNRat input/SNR at output. I really dont understand the definition of SNR in TINA help.

can someone help me understand how to use the various graphs obtained during the noise analysis, to calculate noise figure. My frequency range is 100k to 400Meg

Thanking you,

spanika kamuni

over 8 years ago

0 Loren Siebert 1 over 8 years ago

TI__Genius 13935 points

Hello Spanika,

Since your questions are about modeling and not about specific amplifiers I am moving your question into the modeling forum.

Regards,
Loren

0 John Miller - Sensing over 8 years ago

TI__Mastermind 33170 points

Spanika,

Thanks for the inquiry.
I am an engineer in the WEBENCH Signal Chain modeling team.
We support TINA, as well as our growing suite of online tools.

Your inquiry was forwarded to our Simulation & Models forum.

I will take a look at your circuit and get back to you later today or tomorrow.

Regards,
John

0 spanika kamuni over 8 years ago in reply to John Miller - Sensing

Intellectual 370 points

Schematic.TSCHello John,

Thank you for considering my question. Here I have uploaded my entire schematic for which I wish to calculate the noise figure.

0 John Miller - Sensing over 7 years ago in reply to spanika kamuni

TI__Mastermind 33170 points

Spanika,

Apologies for the delayed reply.
I have tried to create the noise analysis plots you mentioned in your earlier posts.

Unfortunately the resulting plots are not correct.

I will have to check with the TINA vendor to find a root cause and a fix for the problem.
We will try to have this expedited since it is a critical issue for this analysis.
We will do our best to have an update next week.

Regards,
John

0 spanika kamuni over 7 years ago in reply to John Miller - Sensing

Intellectual 370 points

Thank you John,
Hope you People find a solution for this soon.

0 spanika kamuni over 7 years ago in reply to spanika kamuni

Intellectual 370 points

hello miller,

can you please suggest me a way so that i can calculate the noise figure by some Hand calculations by taking the values from the Graphs which i get in Tina.

I tried to calculate dBm/Hz this way.

I took the value of Output noise - 9.12uV/sqrt Hz - Voltage Noise

since my load is 50 ohms - i calculated power- V^2/Hz = (Voltage Noise)^2/50 - Noise Power

then for dBm/Hz i used the formula - 10*log(Noise power) +30

please let me know if this is the right way of aproach for calculating dBm/Hz or correct me if i am wrong.I just want to see the Output noise without any source. since TINA demands a source I put a sine Signal of 1V.

I have one more doubt : I am actually concerned with frequencies between 100k and 220M. so sould i take the voltage noise value at 100k or at 220M........

0 Hooman Hashemi over 7 years ago in reply to spanika kamuni

TI__Mastermind 22825 points

Hi Spanika,
I agree with the way you've computed noise power density (dBm/Hz) from the known value of noise voltage density (nV/RtHz).
So, the 9.12uV/RtHz translates to -87.8dBm/Hz, referenced to 50ohm, according to your formula.

Here is some additional information:
1. Definition of the SNR plot in TINA-Ti: e2e.ti.com/.../1655374

2. More information / example / tricks on TINA-TI noise analysis:
e2e.ti.com/.../what-you-always-wanted-to-know-about-tina-ti-but-were-afraid-to-ask-part-3

Regards,
Hooman

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Noise figure