The Return Path Rules dialog is used to define the values needed to ensure there is a continuous signal return path along the reference layers above and/or below matched signals.
The general rule matching mechanism is described here.
Shortcuts
Menu: Setup
Default Keys: T
Command: Technology
Locating this option
Available from: Setup menu > Technology option > Rules - High Speed - Return Path page
Using the Return Path Rules dialog
On selection, the Technology dialog opens, select Return Path. The existing Return Path Rules for the Technology being used will be presented.
Navigation
Press the New button to add a new entry to the list. To edit an existing entry, select it, the row will be underlined with a red line. The information can then be edited directly in the cell row or in the editing pane below it.
Remove items from the list by selecting it and pressing the Delete button.
Each line in the grid represents a separate rule, rules are used in priority from the top of the list down. Use the Up and Down buttons to re-order the rows to make them more or less significant. These rules are applied in the order defined in this list, until the first match is found. You should therefore have the more specific rules (in terms of layer, area and sub net) defined at the top of the list.
Using the Selected button will report where the selected rule is used in the Technology. Likewise, using the All button will report where all the rules in this dialog are used in the Technology.
Using the editing pane
The appropriate Return Path rule is found for each net item by working down the list of rules until the first match is found. Hence, the order of the rules is important. A match is when the specified Attribute Name and Match Value match attributes of a net item. So the Return Path rule must have the given attribute, and it’s value must wildcard match the value.
Reference Layers
The Above and Below checkboxes are used to define the electrical layers that the matched track needs to be covered. Checking Above will require the track to be covered by copper on the electrical layer above the track layer. Checking Below will require the track to be covered by copper on the electrical layer below the track layer.
Min Gap
The minimum distance required between the track and the edge of the covering copper.
Exclude Voids
Checking this option will cause cutouts in the covering copper not to be taken into account if the item causing the cutout is a pad or via, and it is on the same net as the matched track.
Export and Import CSV
Use the Export CSV button to export the data in your PCB design into a CSV format file. Using the Export CSV option will provide you with a formatted template ready for you to edit in your own data.
Use the Import CSV button to import data back into the PCB design using a CSV format file.
The data in the file represents a spreadsheet of dialog contents with the data headings along the top row.
Related Topics
Net Styles | Track Styles | Design Rule Check | Export CSV | Import CSV