Constraint Groups
Technology file syntax and the technology database together provide a standard mechanism for storing constraints or rules. However, all applications using a technology database may or may not support all the rules stored in the technology database.
Though there is a continuous effort to build rule support in applications as rules become available in the technology database, a time lag of an undetermined length typically occurs between the introduction of a new rule and the support for that new rule being added to an application.
There are three types of constraint groups that you can create:
- Foundry constraint group (foundry)
- Application-specific constraint group
- User-defined constraint group
There can only be one foundry constraint group, but there can be any number of application specific constraint groups and user-defined constraint groups for routing specific nets or net types.
The foundry, application-specific, and user-defined constraint groups may be created automatically during a translation process such as lef2oa, and is based on the information in LEF or DEF files. Other constraint groups may be created by your CAD group, and still others created by the individual layout designer. Some can be stored in a technology database and/or on the design itself.
In Virtuoso Layout Site, you typically have the following constraint groups as a required minimum.
- Foundry constraints group: The foundry constraints group has the absolute minimum rules which must be adhered to manufacture the design.
Setup constraints group: The Setup constraints group typically has the virtuosoDefaultExtractorSetup as the default value. Other possible values are virtuosoDefaultSetup and LEFDefaultRouteSpec.
To download a spreadsheet with constraint-to-application mapping information, click
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