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Dinamycally changing accuracy of simulator during runtime

Hi all,

I am writing as a continuation of the post here: community.cadence.com/.../dinamycally-changing-errpreset-reltol-based-on-rising-edge-of-a-given-signal (which was closed so I cannot continue there)

The verilogA model proposed works fine, however now I need to run the simulation with AMS simulator, rather than spectre and in this case it does not seem to work. The xrun.log file reports:

Error found by spectre during transient analysis `tran'.
ERROR: Invalid event expression '@(DA1:assert)'.
ERROR: Invalid event expression '@(DA2:assert)'.

DA1 and DA2 copies of the code shown in the previous post linked above.

Is it possible to have this working in AMS simulations? How should the syntax be modified?

Also, the goal was to change the simulator accuracy via reltol or errpreset, however now using spectre X these parameters are not meaningful anymore, I should switch say from spectre LX to spectre CX during runtime, is this possible? And how?

or any other way to change the accuracy of spectre X based on an even of a signal during runtime?

Thank you

Best regards

Frank Wiedmann over 1 year ago

For Spectre X, the parameter is called steppreset, not errpreset, see community.cadence.com/.../dynamically-changing-spectre-x-solver-settings
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Andrew Beckett over 1 year ago in reply to Frank Wiedmann

The syntax needs to include the top module name (hierarchy naming conventions are different in AMS, because there is support for more than one top-level). In my case, my top-level schematic is called "top" and then I have a Verilog-A instance within that called "I16" (your case is DA1 or DA2) which has a flag within it called "assert". So I used:

"@(top.I16:assert)"

In addition to Frank's point, I'd like to mention that you should set the default simulation setting to be the tightest you want and then you can dynamically relax it, even at time 0, within the simulation). This is because any parasitic reduction is done at the beginning and cannot be changed during the simulation.

Andrew
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NewScreenName over 1 year ago in reply to Andrew Beckett

works, and thanks for the additional insight about the parasitic reduction

Best regards
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