simple transistor noise calculation and simulation

[maria98]

Hi,
i am looking for simple noise calculation of the transistor and cross verification through cadence simulation. I went through many equations, derivations, but did not find any simple example, which has a simple transistor with its calculation and verification. If any one know, please share. thanks.

 

[KlausST]

Hi,

the way you ask .. lets me assume (that´s all I can do without you giving more details) you did not read or did not understand the documents.

It´s like asking: what´s the easiest way to build a formula 1 car.

There are so much parameters to your question, that a simple answer like "V_noise = n * applied_voltage" is not possible.

The answer surely depends on
* what type of transistor you use, like BJT, MOSFET...
* transistor parameters
* what frequency bandwidth you are interested in
* what output measure you expect like V_pp, I_RMS ...
* circuit, voltages, currents, nodes ....
* and many more...

If there was such a simple answer .... why would one use the difficult ones described in the documents?

Klaus

 

[maria98]

Yes, you are right. Thanks

 

[danadakk]

Simple to do with a simulator (Simetrix) :

Regards, Dana.

 

[KlausST]

Hi,

the Simetrix results ... Is this uV pp or RMS?
I guess they would differ at least by a factor of 5.

Klaus

 

[danadakk]

RMS

Knight

 

[danadakk]

Here is output noise at collector and device alone noise.

The prior table is accumulated noise over the frequency range simulated. The plot is "per-root-Hertz"


Regards, Dana.

 

[BigBoss]

What type of noise you talk about ?? Johnsson ? Flicker ? Shot Noise ? Random Walk ? Pop-Corn ? Pink ??
Noise is a huge chapter.

 

[danadakk]

Random walk, Pink are external sources unless stipulated in Spice, and I see for BJT
spice has no such parameter for either, just one for flicker. PopCorn not "normally"
speced for a BJT, or for that matter most OpAmps.

In the prior sims the BJT does have a flicker parameter, and I am in process of confirming
Johnson is also evaluated in sim....


Regards, Dana.