The Differential Pair Gap Rules dialog is used to specify specify gap rules used by Differential Pairs.
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 - Differential Pair Gap page
Using the dialog
On selection, the Technology dialog opens, select Differential Pair Gaps. The existing Differential Pair Gap rules for the Technology being used will be presented.
Navigation
The buttons to the right side of the dialog are used to navigate the grid, the general common buttons are detailed on the Technology Navigation page.
Using the editing pane
Attribute Name
Use the Attribute name to define how the rule will be selected. From the drop down list, choose from
built in name,
Match Value is used to match the rule against the Differential Pair name or the Attribute name defined.
Wildcards are acceptable in the name, for example HSE*. Use the small button
next to the Match entry to display the
Wildcard Wizard dialog.
The appropriate gap rule is found for each differential pair 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 an attribute of a differential pair, or an attribute on both nets of a
differential pair. So the differential pair or nets must have the given attribute, and it’s value must
wildcard match the value. In particular, you can match the
inbuilt attribute
On Layers
A rule can apply to specific electrical layers. Choose the side Top, Bottom, all Inner or both Outer (Top & Bottom) electrical layers. Alternatively, you can specify a specific layer name, or a wildcard matching string. (So ‘ground *’ would match layers ‘ground 1’ and ‘ground 2’).
Within Areas
If you have any Areas defined in the design, a rule can be defined for a specific named area. Rules can be defined for any combination of Layers and Areas, as required. Similarly, a wildcard string can be defined to match areas. The matching areas must be marked as a Rule Override Area.
Allow Tracks
Use the Allow Tracks in conjunction with Layers and/or Area to create a rule that allows or disallows tracks on that layer or area. You could, for example, disallow differential pairs on Inner layers. This dialog allows you to create a rule for it.
Minimum Gap
The Minimum Gap is the distance used when a differential pair is considered paired (i.e. it runs parallel). You can choose to use the Use the Spacing Rules to derive the gap, or specify a minimum gap. Note that the gap specified here can be smaller than that derived from the spacing rules.
Differential Pairs in the Rules Spreadsheet
The Rules Spreadsheet provides information about the differential pairs in the design. This displays the rules and actual lengths as they are edited in the design. This is presented to you in a dockable modeless bar.
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.
Units
The Units button allows you to locally switch between Metric and Imperial units whilst in this dialog. Once the dialog is closed, the units revert back to the original design units. If switching to different units to the design units, the value typed will be converted when you next enter this page.
Related Topics
Technology Overview | Using Dialog Grids | Differential Pairs Overview | Differential Pairs | Differential Pair Skew Rules | Rules Spreadsheet | Design Rule Check | Export CSV | Import CSV