Noise Analysis

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2014-03-25
2014-03-25
  • Justin Fisher
    Justin Fisher
    2014-03-25

    Good afternoon.

    Is there a way in NGSPICE of plotting spot noise over frequency? Running a noise analysis thus:

    noise v(vout) v1 dec 20 1 10Meg 100
    print onoise_total

    I can see the integrated noise, but what I'd also like to see is the un-integated noise over the simulated range.

    Also, can I create a text printout of all the noise sources at given frequencies? I can do this in Specre and Eldo. Here I notice that if I add the 100 at the end of the noise analysis, I should be able to see noise contributions every 100 Hz. I can see these in the raw file, but that's really difficult to deal with if I have to manually print each source - there are hundreds of them!

    In Eldo I just look at the output log and I get a text table listing each noise source and its contribution at each frequency, so I can see at a glance where the big contributors are.

    Thanks,

    Justin Fisher.

     
  • Justin Fisher
    Justin Fisher
    2014-03-25

    So.

    I found the answer for noise spectrum. It's noise1 and noise 2 as explained in 17.5.39 of the manual.

    The question of a text output for noise contributors remains.