Verilog A: Generate different $random values for each Monte Carlo iteration

Hi,

Interesting question... 

I guess you could do something similar to this:

How to do Monte Carlo mismatch variation on a VerilogA model

That model deck is just a separate .scs (model file) where you add your statements (don't forget to include it in you Model Libraries). You can also define process{} too, for process variations, under that statistical statement.

Let me know if it worked.

Disclaimer: I have not tried this myself. 

BR

/Janko

Janko's proposal is probably the best solution, but another way could be to use How to pass the monte carlo trial (iteration) number to VerilogA module? - this could then be used to set the seed per iteration.  That approach is better if your model is producing a sequence of random numbers rather than modelling a local/global variation effect.

Andrew

Thanks a bunch for that answer !

While Andrew's answer was a simpler solution for my problem (just having a different seed for each MC run), you showed me something I had no idea how to do before and that I'll be using from now on.

So again, thanks a lot for that and have a great day !

Thanks a lot !

Your solution was the simplest for my $random problem (just having a different seed each MC run) so I went with it. Though the values aren't as random as I would like since the seeds are known and using this technique on single runs will always return the same $random values. I was wondering if there was a more volatile environment variable that could be read from verilog A, perhaps something like unix time ?

No worries if such a thing doesn't exist, I'm just curious if you know something.

Have a great day !

Normally people want repeatability in simulations over being different on every run, but you could use $simparam("systime") to get a time-based value (and maybe combine this with the iteration number) as covered in How can you access the current date from a system call in VerilogA?

Really cool ! 

This was what I was looking for.

Thanks a lot : )