2 Replies Latest reply on Jun 10, 2015 4:23 AM by rocco_gruschwitz

    IE3D port reference definition problem


      I just tried the HypLynx v9.2 IE3D capability. To start with, I just exported a very simple small 3D area from a board with a embedded differential strip lines with the top plane as GND and bottom plane as POWER. During the port definition stage, I could only choose either lower reference or upper reference for the differential ports. There is no choice to reference both lower and upper planes. So I did the 3D simulation with lower reference for differential ports first and then again with upper reference for differential ports. To my big surprise, when I check the result S-parameter models and corresponding TDR plots, the 3D simulation results is very different from the HyperLynx 2D solver. The 2D solver gives differential impedance very close 100ohm, which has been verified with my TDR scope on real board. However, 3D simulation tells me the differential imepance is ~150ohm and ~135ohm with lower and upper reference respectively. How could this be? I suspect this has to do with way the port reference is defined.


      Regards, Weiming

        • 1. Re: IE3D port reference definition problem

          I just also did this 3D simulation on a top layer differential micro-strip lines, hence there is no ambiguity about the reference plane, and still it gives ~135 ohm differential impedance. The HyperLynx 2D solver gives ~108 ohm differential impedance. Now I think something is wrong with IE3D while simulating a very simple transmission line.


          Regards, Weiming

          • 2. Re: IE3D port reference definition problem

            Hi Weiming,

            from what you wrote it is hard to say why there is such big difference. It would require to have a look at what you extracted to HL3D.


            Regarding the usage of multiple reference layers it is possible to use both (upper and lower) layer in the simulation. During port setup just assign the positive port to the trace, then the negative layer to the lower layer and directly after this another negative port to the upper layer. Should finally look like the screenshot below.




            Best regards