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Evaluating expression in monte carlo sim

VIPPER

Hi

I am designing a dynamic comparator as my thesis project. I've have encountered a problem while performing monte carlo simulation and evaluating expression with the calculator tool. The expression I am using presents offset voltage of differential pair. During normal simulation everything works corrent but when I run monte carlo, the expression cannot be evaluated.

I've got error:

WARNING (OCN-6038): Results variables are not available for /home2/ic_designs/ams/035/Sim/comparator_tb/adexl/results/data/MonteCarlo.15/1/TRAN_offset/psf/mc1_separate/mc1-001/logFile. Use results() for a list of available results.
\o WARNING (OCN-6038): Results variables are not available for /home2/ic_designs/ams/035/Sim/comparator_tb/adexl/results/data/MonteCarlo.15/1/TRAN_offset/psf/mc1_separate/mc1-001. Use results() for a list of available results.

*Error* ("times" 0 t nil ("*Error* times: can't handle (0.9 * nil)"))
*Error*   Evaluating expression ((((2 * pv("/v_diff" "value" ?result "variables") * cross(VT("/load") (0.9 * pv("/vp" "value" ?result "variables")) 1 "either" nil nil)) / pv("/simulation_end" "value" ?result "variables")) - pv("/v_diff" "value" ?result "variables"))).

It seems that there is no some files which are present during normal sim. Can you help me? I am new in Cadence Virtuoso software.


***

I have another one question. How can I perform simulation to find the minimum setup and hold time during tran sim? I can measure delat time between edges of signals, but in Virtuoso calculator I have to specify which edges (the first one, the second, etc.) will be used during measure.

Best Regards

WD

  • You should use VAR("vp") etc rather than pv("/vp" "value" ?result "variables"). That's looking at the ADE variables, not the value saved by the simulator - and it's not necessarily going to work all the time, whereas the VAR approach should be safe.

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