Learning Forum

[vagadiya]

I am working on simulation of microstrip with Ansys edt 2025 r2 hfss pack and I have question regarding termination of microstrip. For that I am using lumped port and full port impedance is set to 50 ohm. Then is that correct that I am terminating my microstrip with 50ohm or do I need to use lumped RLC for that?

[Takeshi Itadani]

Are you in a situation where both ends of the microstrip line are terminated with a Lumped Port?
If so, when calculating S-parameters, if there is input from one Lumped Port, the other Lumped Port will act as a 50 ohm termination.

[vagadiya]

Thank you for you reply. Yes, both ends of microstrip are terminated with lumped port.So even if I set 100ohm termination on both sides still it will consider 50ohm on other side by default? I am also working on differential line, for which I use 4 lumped port and then I define two differential lines D1 and D2, both ends are terminated with 100ohm. In this case it is also same? 

[Takeshi Itadani]

If you have set Lumped Ports at both ends of a microstrip and want to use a 50 ohm termination resistance, you should set the Full Port Impedance of each Lumped Port to 50 ohms.
To set the differential impedance and common impedance for a differential line, right-click Ecitations in the Project Manager and select Differential Pairs.... There, set the ports (Terminals) to be used as differential pairs, as well as the differential impedance and common impedance.
After analysis, you can plot differential signals by setting Type to Differential Pairs in the Results settings screen. When plotting with Differential Pairs, the impedance settings for each port are ignored and calculations are performed using the differential impedance and common impedance set in Differential Pairs.

[vagadiya]

Thank you so much. This helped a lot.