validLayers – Layer-Purpose Pairs Specification

By default, all purposes of a layer specified in the validLayers constraint are extractable. However, a constraint group can have multiple purposes defined for a layer, forming multiple layer- purpose pairs. You can directly add layer-purpose pairs in the validLayers constraint.

For example, the constraint definition validLayers((METAL1 drawing) METAL2) indicates that the only extractable purpose of METAL1 is “drawing” whereas for METAL2, all the purposes are extractable.

If the validLayers constraint definition has both (METAL1 drawing) and METAL1 specified, the specification limiting METAL1 to drawing purpose is ignored and all the purposes of METAL1 are considered extractable.

Depending on your requirements, you can set the validLayers constraint on a net or on a design. If you add the constraint in the schematic constraint editor, you can define different validLayers for a specified net.

If you set the constraint at the design level, you can restrict the pin layers further than the extract layer level set for Layout XL. This can restrict the pin layers available for creating pins but will continue to extract the design up to the specified extraction level.

Virtuoso Layout Suite XL: Connectivity Driven Editing User Guide
Product Version IC23.1, November 2023