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Input referred noise current through pnoise

joaoff

Hi!


I set a pnoise analysis to measure the input referred noise current of a lock-in amplifier. I used the pnoise analysis because one of the blocks that constitutes the lock-in is a Gilbert-cell mixer.


In the pnoise analysis, I set the Input Source to current in the drop down box and selected my current source at the input of the circuit, but I am only able to plot the result in V/sqrt(Hz), while I desired to plot the result in A/sqrt(Hz). Am I missing something?

The setup is attached.


Thanks!

Parents

  • This is a bug on the form. If you keep V/sqrt(Hz) selected, it will plot the results in A/sqrt(Hz) - the axes will be correct and will show A/sqrt(Hz).

    If you pick V**2/Hz, then the axis shows V**2/Hz - which is also wrong, but the numbers are actually in A**2/Hz.

    I would suggest you log a case with customer support so that we can correct this bug.

    Regards,

    Andrew.

  • in reply to Andrew Beckett

    Hi Andrew

    I have the same problem. I design a TIA. my input is current and output is voltage. I have to use Pnoise analysis because my circuit have switch. when i plot the result to calculate input referred current noise. The result is in V/sqrt(Hz) while the input is current. Is the problem only in displaying the axes? Are the values on the chart correct in A/sqrt(Hz) and reliable?

    regards,

    sahand

Reply
  • in reply to Andrew Beckett

    Hi Andrew

    I have the same problem. I design a TIA. my input is current and output is voltage. I have to use Pnoise analysis because my circuit have switch. when i plot the result to calculate input referred current noise. The result is in V/sqrt(Hz) while the input is current. Is the problem only in displaying the axes? Are the values on the chart correct in A/sqrt(Hz) and reliable?

    regards,

    sahand

Children
  • in reply to sahand1400

    The forum guidelines ask you not to post in old threads, for a good reason. By all means post a new question with a link to the old thread, but a new thread is a good idea.

    The forum guidelines also also you to say which tool versions you're using, also for a good reason.

    I just checked this in current versions (IC6.1.8 ISR18, with SPECTRE 19.1/20.1) and on the Direct Plot form, input referred noise shows up as either A/sqrt(Hz) or A^2/Hz (if the input was a current source and output a voltage source). This (if I remember rightly) was fixed some time ago.

    If you mention which software versions you're using, I can double check the behaviour in that old version (unless it's very, very old).

    Regards,

    Andrew.

  • in reply to Andrew Beckett

    hi, I'm sorry for breaking the forum guidelines. thank you for your kindly reply.

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