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ADE XL Monte Carlo analysis: statistical results are not available

Mike Tian

 Hi all,

     I'm new to ADE XL and I encountered a problem when running  Monte Carlo "Mismatch" only analysis (using IC61 and mmsim07.2). At the end of the simulation it always gives this error: Statistical results for Monte Carlo simulation are not available for the test. I checked the sim log file, it shows the simulation had no error, but it seems like for some reason the results are just not available.The "Detail" field in "Show Mismatch" window shows only "N.A.".

     Could this be due to some set up issue in ADE XL or the PDK model (IBM) i am using? I did go through IBM's reference, and their subckts do have mismatch models, I also have set the global switches in .scs file to enable mismatch.

     Can anyone help me on this? Thank you very much!

 

Mike

    

  • Usually this is simply because you are not including the statistical models. Without knowing the specifics of the model files, I'm not sure how anyone can help - probably best to go to the foundry supplying the design kit.

    Andrew.

  • it is a very new technology and we dont have a complete Design Kit. Attached is the .scs file, I have added myself an example of the statistical models to run the montecarlo using ADE XL. would you please take a look at it if possible? thanks a lot for your answer. Sahel
  • I should also mention that after the montecarlo has finished, in the log file it seems that the simulation has been done successfully for all the montecarlo points. there is only a warning: "mps error: MPSC:bad Handle: (nil)".

  • I've not tried running this in ADE XL (I had to throw something together to replace the veriloga model since I didn't have that), but I suspect that the problem is due to this:

    subckt p_mos D G S
    parameters W=10.0 L=5.0 F=5.0 NC=2 deltaVfb=0
    ...

    The bit in red probably shouldn't be there. The idea is that it is the global parameter which has the distribution (and mismatch then ensures that the variation is done per subckt instance). With this here (and it depends a little on how p_mos is instantiated, which I don't know from your example), the chances are that there is no distribution at all in this parameter, so it sees no statistical variation.

    I'm not sure about the mps error - what subversion of the IC tools are you using (type getVersion(t) in the CIW), and which subversion of the simulator (this will be listed in the simulator output log files near the top)?

    Also, I'm assuming  you were running "mismatch" and not "process" (or both) since your models only have mismatch variation.

    Andrew.

  • Dear Andrew, your point about the red part makes great sense, it was a mistake and I removed it. Nevertheless, the montecarlo still has the same result. to make the situation more clear: 1- I am running only "mismatch" analysis. 2- in answer of "getVersion(t): "sub-version IC6.1.3.500.14", and for the simulator: "Version 6.2.1.431" 3- about the role of deltaVfb: In the model file, I have just changed the threshold voltage from Vfb to Vfb+deltaVfb. In CDF, deltaVfb is a parameter with the default value "0". but the spectre "instParameters" are only "W, L, NC, F". I remark again that the strange part for me is that the log file shows that simulation has been done for all the monte carlo points. Sahel

  • I'm a bit short of time now, so can't really look at this any longer - at least not today (got to do the day job!). Anyway, both IC6.1.3 and MMSIM62 are both old and unsupported - could you use a more recent (and supported version)?

    Andrew.

  • Unfortunately I dont have access to newer versions. thanks for your help and hope you find some more time to continue it! good luck with the job and have a nice weekend! Sahel
  • Hi Andrew, could you maybe answer to this question of mine related to the montecarlo problem: when I introduce a new global parameter with distribution (deltaVfb in this case), how should I configure my CDF with respect to this change? should I make any changes in the "simulation information" part? I would really appreciate an answer to this. Badly stuck with this monte carlo problem! Sahel

  • There's still not really enough information to go on. I'd suggest you contact Customer Support.

    Andrew.

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