Mosaic Instances Generation

A mosaic is an array of instances that belong to the same master. Mosaics are created to allow faster layout generation and editing.

A mosaic is represented in the database as an oaArrayInst object. Each mosaic comprises several evenly spaced identical tiles, as shown in the figure below:

If you create a 3x2 array of instances, as shown in the figure above, you have created a “mosaic instance” with 6 (3x2) tiles.

Virtuoso Layout Suite XL supports the following types of mosaics:

Physical-only mosaics: These are “physical-only” mosaics that have a master, which has no terminal.
Same-connectivity mosaics: These are mosaics that share the “same connectivity” across all their tiles because each terminal of the mosaic master is mapped to an edited cellview instance terminal.

The master of same-connectivity mosaics can also contain unassigned shapes that are treated as “unassigned shapes” in the master of scalar instances.

Layout XL enables you to create dummy mosaic instances that can be tied to an existing net on the mosaic. These dummy mosaics, if active—tied to a net other than the power or ground net—can be backannotated to the schematic as mfactored instances.

Dummy mosaic instances can be used as fillers in the layout to cover large design areas. When backannotated to the schematic, these instances can be represented as single, mfactored instances.

Dummy mosaic instances in the layout do not need the schematic counterpart to be always available, but backannotating these dummy mosaics to the schematic ensures that no instance mismatches are reported during a layout versus schematic run.

See Creating Dummy Instances and Dummy Instances Backannotation.

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