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Electronics

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Inconsistent results between Terminal Wave Port and Terminal Lumped Port…

    • alexandre-antoi.bourrieau
      Subscriber

      Hello,

      I am trying to simulate a 100 ohm differential impedance FCC flat cable (Molex) but I can't find consistent results when using the Lumped or Wave terminal ports.

       

      My aim is to simulate 24 inches long cable. But as it is very processor demanding, I want to simulate a portion of the cable (here 5 cm) and virtualy increase the lenght of the cable by de-embeding it.

       

      Problem is I cannot use lumped ports because using lumped port do not give the possibility to use de-embeding for extend lenght of cable. So I need to to use wave ports.

      The structure of the cable  is following and I am trying to simulate common signal to get 50 ohm impedance :

      1726314639906.png1726314668170.png

      When using terminal Lumped port, I got 50 ohm result for a single signal with two GND around it (GND/ SIG / GND ) which is consistent with the 100 ohm diff cable :

      1726314713115.png

      Unfortunatly, when using terminal wave port, I got 38 ohms instead of 50 :

      1726314858992.png1726314872267.png

      I have tried to modify a little the port geometry so that there is 3 digit scale for the E-field on the wave port, and a better e-filed vector distribution but I still get 38 ohm instead of 50 ohm...

      1726314946490.png1726314965440.png

      Do someone have any idea to get better result using wave port ?

       

      Thanks you very much !

    • alexandre-antoi.bourrieau
      Subscriber

      I think the geometry for my port is OK because if I increase it like this, I got oscillation on the TDR response, but still 38 ohms:

    • Aymen Mzoughi
      Ansys Employee

      You can tighten the maximum delta z0 in the solution setup if more accuracy is needed:

    • alexandre-antoi.bourrieau
      Subscriber

      I got the same result, even by using "Maximum Delta z0" = 0.1% instead of 2%...

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