OPAMP noise contribution to the out orcad pspice

Thread Starter

algio

Joined May 29, 2011
5
I have a circuit with several OPAMPs where I can get total power spectral density of the output using NTOT(ONOISE), and I also can get the contribution of any resistor i.e: NTOT(R1) to the output.

But... Is it possible to get the total contribution of an opamp?
I would like to do something like NTOT(U1) or NTOT(X_U1) to get it, but unfortunately does not work...
Any ideas?
 

Audioguru

Joined Dec 20, 2007
11,248
Very old opamps like the antique 741, LM324 and LM358 have high noise levels.
Modern audio opamps have low noise levels.
Your simulation program might not have models of them.
 

Thread Starter

algio

Joined May 29, 2011
5
I use the opa357. I downloaded the model from the web. And I believe it has the noise information included, because it says that includes:
* INPUT VOLTAGE NOISE WITH 1/F
* INPUT CURRENT NOISE
 

Audioguru

Joined Dec 20, 2007
11,248
The OPA357 is a pretty good low noise video opamp.
Texas Instruments probably has a model of it on their website.

Nobody makes and tests circuits anymore?
Is everything just a simulation that might be correct or wrong?
 
Top