How to Add Return Path Vias when Routing High-Speed Signals

When working with high-speed signals, having a good return path is crucial for signal integrity. For some high-speed nets, return path vias should be incorporated every time a via is placed. While these can be added manually after routing is complete, it can be tedious and increase the possibility of errors. With the high-speed option in Allegro PCB Designer, return path vias can be configured and added automatically during routing.

This quick how-to will provide step-by-step instructions on how to configure and add return path vias when routing single nets with the high-speed functionality in Allegro PCB Designer.

How-To Video

Configuring Return Path Via Settings

Step 1: Open the desired design in Allegro PCB Designer with the High-Speed Option enabled.

Step 2: Select Route > Connect from the menu or the Add Connect icon from the toolbar.

Step 3: Click to start routing a trace.

Step 4: To configure settings, right-click and select Return Path Vias > Settings.

Step 5: The Return Path Via Setup window opens. Select the ellipsis for Return Path Net to assign a net name.

Step 6: Select the desired net name and click OK.

Note: If a voltage property has been defined for nets in the design, select DC Nets to filter the nets.

Step 7: Select the ellipses for Return Path Via to select the padstack.

Step 8: Select the desired padstack and click OK.

Step 9: Set the desired via spacing under 1 Via. By default, the minimum spacing is configured.

Note: The 1 via pattern adds one return path via next to one of the trace vias. Here you can configure the:

• Space X: Circumference-to-circumference distance of the vias.
• Angle: The angle at which the return path via is located with respect to the trace via.
• Mirror-Geo: Mirrors the location of the return path via as shown below.

Step 10: Click OK.

Placing Return Path Vias

Step 11: Right-click in the canvas and select Return Path Vias > 1 Via to associate the via.

Step 12: Double-click while routing to activate via placement. Via placement mode will activate as normal and the return path via will attach to your cursor separate from the trace.

Step 13: Click to place the vias.

Step 14: Continue routing the trace. Right-click and select Done when finished.

Adjusting Vias

Step 15: Select Route > Slide from the menu or the Slide button from the toolbar.

Step 16: Select one of the vias. The trace and return path via are both attached to the cursor.

Step 17: To adjust each via separately, right-click and de-select Return Path Vias Group while the group is selected.

Step 18: When finished, right-click and select Done.

Wrap Up & Next Steps

Accelerate the PCB layout for high-speed designs and quickly add return path vias while routing with the high-speed functionality in Allegro PCB Designer.  Learn more about solving common issues for high-speed designs with our e-book.