OPAMP noise contribution to the out orcad pspice

Discussion in 'General Electronics Chat' started by algio, Jan 25, 2013.

  1. algio

    Thread Starter New Member

    May 29, 2011
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    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?
     
  2. Audioguru

    New Member

    Dec 20, 2007
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    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.
     
  3. algio

    Thread Starter New Member

    May 29, 2011
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    0
    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
     
  4. Audioguru

    New Member

    Dec 20, 2007
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    896
    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?
     
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