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How to tell spectre (in ADE L) to enable "monte carlo" mode

itos

(EDITED)

Hello,

I am using an ST PDK ("ArtistKit") and I want to run a SIMPLE sim with local variations turned on. What I mean is that in a SINGLE RUN in ADE L, when I have two identical Common Source stages, the outputs should be different. I want to handle/plot the data entirely in ADE L.

Now I configured every single parameter that has to do with "Monte Carlo", "statistical" but if I run from ADE L the outputs of the 2 CS stages are just always identical, meaning that randomness to the transistors is applied and hence local variations do not work.

Instead now if I open ADE XL, load the ADE state from there and import the corners (as outlined in the documentation) it WORKS! But ONLY if I choose Run -> Monte Carlo Sampling (and as a workaround enter 1 Run). It does NOT work if I choose Run -> Single Run.

1.) Is there any way to enable the varations without monte-carlo statement from within ADE L? I neither like nor need ADE XL

2.) What is the proper "hack" to use Monte Carlo for a single run then?

For now I bite the bullet and play around in ADE XL. All I want is to have 2 runs (manually started by me!) to show their transient ouplots plots on top of each other. Although my netlists says:

mc1 montecarlo numruns=1 seed=1984 variations=mismatch sampling=standard \
    donominal=no scalarfile="../monteCarlo/mcdata" \
    paramfile="../monteCarlo/mcparam" savemismatchparams=no  \
    paramdumpmode=yes savefamilyplots=yes savedatainseparatedir=yes \
    wfseparation=yes {

[...]

I still get this warning when running:

Warning from spectre during Monte Carlo analysis `mc1'.

    WARNING (SPECTRE-16006): mc1: Redundant monte carlo analysis was encountered. Neither scalar data nor waveform data will be saved.

Finally, ADE XL starts the sims with SOA (Safe Operating Region) checks enabled although I have explicitely disabled them everywhere. This causes the sim to hang (1000s of devices). I have to hack around in the output directory and manually change the flags between netlist generation and sim start. This is probably too process specific to be solved here but it's one of the many reasons why I don't want/can't use ADE XL.

Thanks!

  • Andrew Beckett

    Monte Carlo is not supported within ADE L. Simple as that. ADE XL provides the infrastructure to analyse the results, as well as what's needed to set up the simulation (even if it's a single point simulation) - the run mode causes the montecarlo analysis statements to be added into the spectre netlist.

    I don't know why the checks have been enabled - best place is to check the netlist and see whether the the dochecklimit option has been turned off (it's yes by default in spectre). You may be able to use a sledgehammer approach (maybe the kit is setting it somewhere) by adding "-docl" to the userCmdLineOptions field in Setup->Environment for the test.

    If you don't like ADE XL, perhaps you could look at the new ADE Explorer in IC617. This is the next generation of ADE tools and is the single test environment and has been designed to have an ADE L like use model. It does however allow you to run corners and monte carlo if you want to and add specs to your output expressions (if you want to) but because it's only ever dealing with a single test it retains most of the simplicity of ADE L.

    Regards,

    Andrew.

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