Clearance Rule Sub-Scopes for Differential Pairs

Altium Designer includes Sub-Scopes as part of its clearance rule checking in the PCB Editor, specifically aimed at addressing the issue of clearances pertaining to Differential pairs.
Previously, a board containing n Differential pairs would require the time consuming effort of setting up n+1 clearance rules – to obtain the desired clearances between primitive objects belonging to different nets of the same Differential pair, and between those objects belonging to different nets of different Differential pairs. These Sub-Scopes allow Designers greater control over the constraints applying to differential pairs.

The Sub-Scopes can be found in the PCB Rules and Constraints Editor under the Design menu as seen in the accompanying image.

These Sub-Scope rules are resolved independently of the Differential Pair Routing rule which defines the spacing of the originally routed pair . As such, Designers often need to constrain what happens to such spacing between either primitives that lie within one Differential pair or for spacing between Different, Differential pairs during further routing.

Consider the following design image...

The Differential pairs have been routed according to the Clearance set in the new scope, Different Differential Pair. In this example, the distance to be maintained between different Differential pairs was set by this scope at 50mil.

The use of the Sub-Scope Same Net Only applies clearance constraints to address primitives contained within the one trace in one Pair.

In the following example, vias are to be placed on one of the pair traces but the design requires that a distance be kept from the originating pad.
The solution is to edit query 1 as IsPad and query 2 as IsVia and assign the Sub-Scope as Same Net Only and set the required Distance - in this case, 50mils.

The use of the Sub-Scope Same Differential Pair allows control over the spacing of the pairs and objects within the pair nets.

The following example is based on design rules which use this new Sub-Scope to DRC the spacing during a route process which 'pushed' the Differential pair.

The Clearance rules associated are set with the Differential Pair Routing 'Minimum Gap' in mind.
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This is to ensure consistency within the Differential Pair. Designers could also set up a 'Cascade' circumstance where the larger of the two values is the Clearance rule Sub-Scope whereby the DRC will check against the minimum clearance allowed in the Same Differential pair independently and then check the Differential pair routing Rule to see if the current spacing is still within the limits of that set as the maximum Gap at the uncoupled Length.