Differential Pairs in HFSS Transient Network
For post process calculation of differential pairs in Transient Network problems, you can assign differential pairs in spectral terminal problems for transient designs. For Transient Composite Excitation problems differential pairs are not supported.
In Transient Network, you can solve the single-ended matched terminal problem. HFSS Transient uses the same post processing algorithms that HFSS uses to compute the differential and common modes for spectral values. In addition, a separate algorithm computes the differential pairs values for transient data. You can switch between single-ended and differential views of both spectral and transient data. Renormalization of spectral data is supported, but renormalization does not apply to transient data.
The dialog for transient Differential pairs includes columns for Enabled and Matched. Passive ports are not shown in the diff pairs setup dialog box.
The table row shows the check box for the newly defined pair as Enabled. Unchecking the box disables the definition for that pair. This can be useful if you later want to redefine terminal normalization, without having to remove the defined pair altogether.
A check box for "Matched" for each differential pair indicates whether to use matched or differential and common impedances. This Matched check box also appears in driven terminal designs and uses the same postprocessing semantics. Matched is the "natural" in general frequency dependent characteristic impedance of the line. For multiple terminals it describes the coupled nature of such lines and is therefore a dense matrix relating voltages and currents on the line. A matched terminal project is analogous to an unrenormalized wave port in driven modal where the s-parameter is referenced to the 'natural impedance' of the port cross-section. If you unselect Matched, you renormalize to a set impedance for the diff or common modes.The transient solver uses the Matched value when the Design setting "Apply when solving" is selected.