W-element Analysis

W-elements are a distributed model for transmission lines used in certain HSPICE-compatible circuit simulators. For designs containing traces and planes, SIwave can export the W-element in either single frequency or tabular format.

To export the W-element in SIwave:

  1. Open a project containing traces and planes.
  2. Select the layer containing the trace you want to analyze.
  3. Select the trace.
  4. Click Advanced > W-element Analysis.

    The Export W-element window appears.

    Export W-Element Window

  5. Leave the Export W-element window open and click in the Modeling workspace to draw a cross-section over the trace.

    From the following image, the trace is highlighted in yellow and the cross-section is the line intersecting it (indicated by a red arrow).

    Trace and Cross-Section

    If you make a mistake, you can click Redraw cross section to retry.

    6. Click OK.

    Using the cross-section you entered, the Cross-section visualizer updates, and the list of conductors populates:

    Conductor Table

    The grid displays the following for each conductor:

    • Name – conductor name.
    • Cross Section – indicates the shape of the cross section.
    • Width – can be edited here directly, or imported from the Layer Stackup Wizard by selecting Use width/pitch in W-element.
    • Pitch – can be edited here directly, or imported from the Layer Stackup Wizard by selecting Use width/pitch in W-element.
    • Orientation – fixed, left, or right.
    • Engage – enabling this check box engages the conductor in IL/RL/FEXT/NEXT simulations.

    From here, you can:

    • Edit the Width and Pitch values directly in the table.
    • Add aggressor(s) to the left, right, or on both sides of a selected victim element.
    • Delete an element by selecting it and clicking Delete element.
    • Export the W-element:
      • Select Single frequency W-element model and enter a frequency for export, or select Tabular W-element model and click Set frequency range.
      • Click Export to save the W-element as a Spice (*.sp) file, or click Export to 2D Extractor to save the W-element as a VB script (*.vbs) and run it in 2D Extractor. Generating this script launches a prompt asking if you want to run the script in Electronics Desktop. Consult the Q3D Extractor/2D Extractor help for instructions on running an analysis in 2D Extractor.
    • Compute insertion/return loss and time domain crosstalk.
  6. Click Close to exit the Export W-element window.
Note:

You can also access the Export W-element window from the Layer Stackup Wizard.