HyperLynx 8.2.1 does not support mode conversion for more than four SE ports. However you can do this in HSpice. For details and example netlist see the following link:
We realize this is a useful feature and have it planned for an upcoming release.
In the meantime, there is a workaround using Modua from HyperLynx 3D (which is part of the HyperLynx SI install). It does take some time to do the conversion, but it works.
1. 1. Open Modua.exe from your HyperLynx install at …\SDD_HOME\IE3D\exe\ and then click Yes and OK.
2. 2. Load in the S-parameter by Selecting File -> Open (and select All Files *.*).
3. 3. Once loaded, select Process -> Differential Conversion. Wait for the next dialog to pop up.
4. 4. Click the Differential Port button. Select two single-ended ports you want to combine into a differential port. Repeat this process for all the ports in the S-parameter.
5. 5. Once ports are mapped, click OK. When the Save dialog comes up, enter a name for the new differential S-parameter and click OK.
6. 6. Note that the resulting S-parameter has a reference impedance of 50 ohms on each port. If desired, you can change the normalization impedance to 100 ohms for each port in Modua by selecting Control -> Terminating Impedance or in the HyperLynx Touchstone Viewer by selecting Convert -> Re-Normalize.
Looks like you forgot to set the right termination impedance in Modua. It defaults to 50 ohms - see my previous post... you probably want to set it to 100 (easily done in the Touchstone Viewer).