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Noise contribution of an instance

svcher

Hello,

Is there a way to get Spectre to output total noise contributed by a certain instance?  The instance may be a sub-circuit, in which case I'd like to know the sum of all contributions from elements inside of that sub-circuit. I understand that there is "noise summary" feature in ADE, but can this be done outside of the ADE, using stand-alone SpectreRF and/or SpectreMDL?

  Thanks!

  • Andrew Beckett

    The ADE noise summary form has the ability to summarise the noise for a particular level of hierarchy - and then you can see the total for each hierarchical instance at that level.

    For standalone use, there's a command called "noisesummary" (which I don't think is documented), which you can invoke with "noisesummary -help" which you can run on an existing noise data set and it will produce a summarised dataset that you can then open in ViVA or OCEAN which gives the total for the hierarchical instances at a certain level of hierarchy.

    Regards,

    Andrew.

  • svcher
    Thank you Andrew, this would have been a good solution for me, unfortunately "noisesummary" does not work:

    > noisesummary -help
    Usage: noisesummary result_dir dataset_name hierarchy_level [optional]sweep_number

    This is what I do:
    > spectre noitest.scs
    ...
    > noisesummary noitest.raw no1.noise 1

    This is what "noisesummary" prints out in response: "Error: The special dataset is not exist."

    Any idea what I am doing wrong? The Spectre deck is below, in case you need to take a look.

    ==============================
    // Version info: Version 15.1.0.498.isr6 32bit -- 31 May 2016
    simulator lang=spectre
    op options rawfmt=psfascii temp=25
    subckt x1 A B
    r1 (A 1) resistor r=100
    r2 (1 B) resistor r=200
    ends
    subckt x2 A B
    r1 (A 1) resistor r=50
    r2 (1 B) resistor r=250
    ends
    i1 (3 2) x1
    i2 (2 1) x2
    i3 (1 0) resistor r=80
    // voltage noise at node 3 is sum of noises in i1, i2 and i3
    no1 (3 0) noise freq=1
    ==============================
  • Andrew Beckett

    OK, two things you need to do:

    1. Take out the rawfmt=psfascii from the options line; with that the noisesummary executable will crash (given the right argument) - it's clearly not designed with anything other than binary psf in mind
    2. Use "noisesummary noitest.raw no1-noise 1" (the dataset is called no1-noise).

    Looking at the result, it spits out a new logFile which wouldn't normally be seen by ViVA or OCEAN unless you move the noiseSumLogFile to be called logFile instead. However, I'm assuming (from the rawfmt setting) that you are parsing the psfascii, so probably all you need to do is:

    psf -i psf.noisesummary -o noisesummary.ascii

    to convert it to ASCII.

    Regards,

    Andrew.

  • svcher
    That worked, both "noisesummary" and the "psf". Thanks Andrew.

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