Length Matching

Matching routed path lengths is a common timing goal.​​

The idea is to match the path lengths of objects, like Nets - within a matching Tolerance - in a collection of these Objects, like a Class of Nets:

  • Match Nets in a Class

  • Match FromTOs in a Group

  • Match Groups in a GroupSet

  • Match Series Component Groups in a GroupSet

There's another way to understand matched path lengths:

Route all the matched paths to within the matching Tolerance of the longest routed path in the collection.


In fact, this is exactly how the Router understands matched lengths. It will route the longest path and 

pull the shorter paths to within the Tolerance of this longest path.

If the longest path 'runs away' and routes uncontrolled very long, the other matched paths will also be excessively long, since they must be within Tolerance of this longest routed path in the matched collection.

To route a shorter range, prevent 'RunAway' of the longest by capping the longest path maximum and keeping the matched range short.