Learning Forum

[wang jian]

When I carried out transient simulation in AEDT, I used dynamic link function to import hfss 3d layout model to build simulation circuit schematic. Simulation results in hfss 3d layout are passive. However, the simulation circuit schematic is built in the AEDT, and the software keeps this warning when the simulation is carried out. What is the reason?

[Dan Dvorscak]

That warning means that the state-space macromodel the Circuit tool uses to solve the s-parameters in the time domain itself has passivity issues, not the s-parameter data coming from HFSS. A common cause for this is if the state-space model ends up being non-passive above the original bandwidth of the incoming s-parameters. 

As for what to do next, I don't think you need to do anything unless you think the results look suspect. If the tool detects that the simulation is going unstable due to the non-passivity, it will automatically re-start the simulation with passivity enforcement enabled. Based on the log file, that is not happening here, so I'm not immediately concerned.

Best regards,

-Dan