Computing Insertion/Return Loss and Time Domain Crosstalk (HFSS 3D Layout)

From the Export W-Element window, you can compute and plot insertion loss (IL), return loss (RL), far-end time domain crosstalk (FEXT), or near-end time domain crosstalk (NEXT).

Prerequisites:

• Use the Layer Stackup Wizard to calculate trace width/pitch, impedance, or differential impedance.
• Export W-element.

To calculate and plot IL/RL/FEXT/NEXT:

1. From the Export W-Element window, click IL/RL/FEXT/NEXT to open the Frequency Sweep window.

   

2. Add, remove, and edit frequencies as appropriate. Click Preview to preview the number of frequency points.
3. Click OK to open the IL/RL and Time Domain Crosstalk Plot window to the L/RL tab.
4. Select the FEXT/NEXT tab to view the crosstalk plot instead. While the plot computes, a green progress bar displays the progress. When it is finished, the selected plot appears.

   

   

   For IL/RL plots, you can adjust the Length or click Set frequency range to change the frequency range of the plot.

   For FEXT/NEXT plots, you can adjust the Tline length (trace length); edit the Rise time, Stop time, and peak Voltage of the driver attached to the aggressor net; or modify the driver Input Impedance value. This impedance is also used to terminate all transmission lines in the specified cross-section.

   If you wish to export plot data, click Export Options:

   • For IL/RL plots, select Export w-element schematic to circuit (in *.aedt format) or Export touchstone file.
   • For FEXT/NEXT plots, select Export w-element schematic to circuit (in *.aedt format) or Export .csv file.

   If you change values and need to regenerate the plot, click Recompute.

   Right-clicking in the plot enables additional plotting actions.

5. Click Close to exit the plot window.