• Skip to main content
  • Skip to search
  • Skip to footer
Cadence Home
  • This search text may be transcribed, used, stored, or accessed by our third-party service providers per our Cookie Policy and Privacy Policy.

  1. Community Forums
  2. Custom IC Design
  3. ADE-XL Mismatch Monte-Carlo Simulation Issues

Stats

  • Locked Locked
  • Replies 2
  • Subscribers 126
  • Views 8339
  • Members are here 0
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

ADE-XL Mismatch Monte-Carlo Simulation Issues

jsillman
jsillman over 2 years ago

Hello,

I'm a student and I'm trying to figure out how to use the Monte Carlo simulation built into Cadence Virtuoso's ADE-XL simulation tool for personal research. Right now, I am just trying the mismatch sampling simulation on a simple inverter:

My university uses PTM (Predictive Technology Models) which had no built-in statistics blocks for the models we use. I added my own statistics block and made educated guesses for the expected distributions for 10 of the model parameters. Below is my statistics block section:

statistics {
process { // process: generate random number once per MC run
vary vth0n dist=gauss std=5 percent=yes
vary toxn dist=gauss std=5 percent=yes
vary cgdon dist=gauss std=10 percent=yes
vary cjn dist=gauss std=10 percent=yes
vary cjswn dist=gauss std=10 percent=yes
vary mjn dist=gauss std=2 percent=yes
vary pbn dist=gauss std=5 percent=yes
vary mjswn dist=gauss std=1 percent=yes
vary pbswn dist=gauss std=5 percent=yes
vary cgson dist=gauss std=10 percent=yes

vary vth0p dist=gauss std=5 percent=yes
vary toxp dist=gauss std=5 percent=yes
vary cgdop dist=gauss std=10 percent=yes
vary cjp dist=gauss std=10 percent=yes
vary cjswp dist=gauss std=10 percent=yes
vary mjp dist=gauss std=2 percent=yes
vary pbp dist=gauss std=5 percent=yes
vary mjswp dist=gauss std=1 percent=yes
vary pbswp dist=gauss std=5 percent=yes
vary cgsop dist=gauss std=10 percent=yes
}

mismatch { // mismatch: generate a random number per instance
vary vth0n dist=gauss std=5 percent=yes
vary toxn dist=gauss std=5 percent=yes
vary cgdon dist=gauss std=10 percent=yes
vary cjn dist=gauss std=10 percent=yes
vary cjswn dist=gauss std=10 percent=yes
vary mjn dist=gauss std=2 percent=yes
vary pbn dist=gauss std=5 percent=yes
vary mjswn dist=gauss std=1 percent=yes
vary pbswn dist=gauss std=5 percent=yes
vary cgson dist=gauss std=10 percent=yes

vary vth0p dist=gauss std=5 percent=yes
vary toxp dist=gauss std=5 percent=yes
vary cgdop dist=gauss std=10 percent=yes
vary cjp dist=gauss std=10 percent=yes
vary cjswp dist=gauss std=10 percent=yes
vary mjp dist=gauss std=2 percent=yes
vary pbp dist=gauss std=5 percent=yes
vary mjswp dist=gauss std=1 percent=yes
vary pbswp dist=gauss std=5 percent=yes
vary cgsop dist=gauss std=10 percent=yes
}
}

Note that I instantiated these parameters at the top of the .scs model file with values from the original PTM model. Now, when I run a Process Monte-Carlo simulation, the result of the simulation turns out the way I expect it to look. However, when I run a Mismatch Monte-Carlo simulation, there is no deviation from the nominal simulation whatsoever. All iterations of the simulation land on the nominal values. I looked at the output log for each iteration and I notice this line:

"Notice from spectre during Monte Carlo analysis `mc1'.
Number of defined mismatch parameters: 20, number of non-referenced mismatch parameters: 20. Number of mismatch instances: 0."

I take this to mean that the instances from the schematic are not being recognized as mismatch instances, so no mismatch is being applied in the simulation. Does anyone know how to get ADE-XL to recognize the instances from my schematic file? Help would be greatly appreciated!

  • Cancel
  • ShawnLogan
    ShawnLogan over 2 years ago

    Dear jsillman,

    jsillman said:
    and I'm trying to figure out how to use the Monte Carlo simulation built into Cadence Virtuoso's ADE-XL simulation tool for personal research. Right now, I am just trying the mismatch sampling simulation on a simple inverter:

    As you probably know, ADE-XL is no longer actively supported by Cadence. Hence, I might suggest you consider migrating to ADEL Explorer or Assembler. The transition is quite easy as from Explorer or Assembler you can directly import your ADE-XL state file and it will convert it to the maestro format supported by Explore and Assembler. Assembler and Explorer have far more features than ADE-XL and are supported.

    Nevertheless, although I don't know all the details of your models, the definition of its parameters, and how you are instantiating your model file, I would consider simplifying the situation and perform a simple Monte-Carlo simulation of a voltage source emulated by an ideal current source and resistor. There is an example given in the support article at URL:.

    support.cadence.com/.../ArticleAttachmentPortal

    The Troubleshooting article illustrates how to define the process and mismatch parameters for the resistor and then performs a Monte-Carlo simulation of three voltage sources with different variation parameters and displays the results. I would suggest you run this example using both Process Mismatch and Mismatch only and determine if the Mismatch only results still show no variation in ADE-XL.

    Shawn

    • Cancel
    • Vote Up +1 Vote Down
    • Cancel
  • jsillman
    jsillman over 2 years ago in reply to ShawnLogan

    Thank you for sending me to this trouble-shooting article! It helped me find out what was wrong with my syntax very promptly. The problem has been solved.

    • Cancel
    • Vote Up 0 Vote Down
    • Cancel

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.

© 2025 Cadence Design Systems, Inc. All Rights Reserved.

  • Terms of Use
  • Privacy
  • Cookie Policy
  • US Trademarks
  • Do Not Sell or Share My Personal Information