Differential Pairs Routing

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Modified by Admin on Nov 6, 2013

Rule category: Routing

Rule classification: Unary

Summary

This rule defines the minimum clearance between primitives on different nets within the same differential pair.

Constraints

Default constraints for the Differential Pairs Routing rule.

Min Gap – specifies the minimum permissible clearance between primitives on different nets within the same differential pair.
Preferred Gap – specifies the preferred clearance between primitives on different nets within the same differential pair.
Max Gap – specifies the maximum permissible clearance between primitives on different nets within the same differential pair.
Max Uncoupled Length - specified the value for the max uncoupled length between positive and negative nets within the differential pair.
Layers in layerstack only – allows you to display and edit the width constraints for just the defined signal layers in the layer stack. When enabled, only the layers in the stack will be displayed in the Layer Attributes Table. When disabled, all signal layers will be displayed.
Layer Attributes Table – displays all signal layers or only those defined in the layer stack, as controlled by the Layers in layerstack only option. The minimum, maximum and preferred gap are displayed, as well as other layer-specific information. The gap fields can be set globally by defining a value in the individual gap constraint fields, or individually by typing a gap value directly into the table.

When defining values for the minimum, maximum and preferred gap, the Layer Attributes Table will highlight any invalid entries by using red text. This could happen, for example, when you specify a minimum constraint value that is greater than the maximum constraint value. The incorrect rule definition is further highlighted by the rule name becoming red in both the folder-tree pane and the respective summary lists, in the PCB Rules and Constraints Editor dialog.

How Duplicate Rule Contentions are Resolved

All rules are resolved by the priority setting. The system goes through the rules from highest to lowest priority and picks the first one whose scope expression(s) match the object(s) being checked.

Rule Application

Online DRC, Batch DRC, interactive routing, autorouting

Notes

Clearance checking between primitives associated to different nets of the same differential pair is governed by the value for the Min Gap constraint defined for that layer as part of the applicable Differential Pairs Routing rule.