macromodelling with spice

hi

if i simulate a pcb structure (a microstrip trace) with an 3d electromagnetics simulator to create a macromodell (s-parameter touchstone file), then do i have to connect terination resistors in the em simulation setup?

if i connected a 50 ohm termination resistor in the em simulation, then can i use the macromodell with different termination resistor value in the circuit simulation (when i use the s-parameter macromodel, for example in Agilent ADS, or spice...)? will it cause incorrect results?

I think the S parameter results should depend on the actual termination: for example if its matched then there will not be resonances... and then if i use the macromodell with unmatched termination resistors in circuit simulation it will not to cause resonances anymore.
if i reuse the macromodell and use different termination in the circuit simulation, then the macromodel will not behave differently from the case of the first used termination value. is it right?
the problem is in the em simulation we can not use the correct termination, since it comes from IBIS buffer models and those are not compatible with EM simulators.
so, how much usable an s-parameter macromodell?

Hello buenos,


I think your problem can be solved if you use EM Simulator with Circuit simulators...
One such solution is use AWR MWO with CST MWS or Sonnet or Vector Fields Concerto...i.e create the Microstrip trace/structure in EM simulator the use it as a subcircuit with different terminations in MWO...

Or Extract the spice model or equivalent of the Microstrip trace model using Sonnet/MWS & then use the circuit simulator such as MWO...Instead of S-parameter file export!

---manju