Connectivity Extraction Use Model

When you open a design in Layout XL, by default, connectivity extraction is not run. If you are opening the design for the first time, you can run the extractor explicitly using the Connectivity – Update – Extract Layout command to generate an up-to-date connectivity model for the entire design. The same applies if you have edited your design in a non-connectivity-aware environment such as VLS L.

• Automatic Connectivity Extraction: To automatically run connectivity extraction when Layout XL is launched, use the extractRunOnInit environment variable. However, this means that extraction is run even if it is not required and can adversely affect the performance of Layout XL during startup.
  Cadence recommends that you do not enable the extractRunOnInit environment variable by default, but that you use the Connectivity – Update – Extract Layout command when you know it is required.
• Incremental Connectivity Extraction: By default, Layout XL updates the connectivity and generates violation markers when you create, delete, or otherwise modify the shapes in your design either manually or automatically, using editing tools. This incremental extraction capability is controlled by the Update connectivity when design is modified option on the Connectivity Form.
• The connectivity and violation markers generated are saved in the design database and, therefore, are present the next time you open the design in Layout XL. Unless you edit your design outside Layout XL, you do not need to run extraction again when you re-open a design.
• Bottom-Up Connectivity Extraction: Bottom-up connectivity extraction is enabled by setting the extraction Scope to Current Cellview and Cellviews in Hierarchy in the Extract Layout Form.
  During bottom-up connectivity extraction, a series of connectivity extraction runs are performed on lower-level cellviews in a bottom-up order. This means the connectivity extraction starts from the lower-level cellviews in the hierarchy up to the current edited cellview. The advantage of running a bottom-up-extraction is that it does not require you to open each of these cellviews in a graphical window before being able to extract them. However, the extraction run can only extract connectivity from the cellviews that are within the specified hierarchical depth below the current edited cellview.
  Each bottom-up connectivity extraction run verifies the connectivity of the objects in the cellview being extracted. During the verification, if a connectivity mismatch is found for an object, the extractor either updates the connectivity on the object, if possible, or creates a marker in the cellview. The markers generated by the extractor can be viewed from the current edited cellview by setting the scope of the Annotation Browser to Current Cellview to Depth.
• Extractor Performance: The performance of the connectivity extractor could be impacted if the design has many overlapping, identical shapes. To prevent the performance impact, ensure that overlapping, identical shapes are removed before connectivity extraction is run.

Related Topics

extractRunOnInit

Connectivity

Extract Layout Form

Annotation Browser Assistant

Enabling and Disabling Incremental Extraction

Extracting a Top-Level Design

Extracting Hierarchical Cellviews

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