Exact and Non-Exact Matches for Cloning

To clone components, you select the structure to be replicated (the clone source) and the software searches the design for target structures that match the source. You create a clone when you generate a target structure in your design.

To be considered a valid target, the instance master referenced by the components in the target must exactly match the instance master referenced by the components in the source. A target that also matches the source in terms of connectivity is considered an exact match. A target that tolerates slight differences in connectivity is a non-exact match, also known as a mutant clone.

You can use the options in the Generate Clones form to specify which differences are tolerated.

• Allowed Permutation considers pin permutability when searching for matching target structures. If an appropriate permuteRule Property is defined for the device in question, and if permuting the pins on a device results in a match, then that match is reported (but only if no matching targets were found without permutation).
  Example
  Two NMOS devices connected by their D terminals will match two NMOS devices connected by their S terminals, provided there is a permute rule in place that allows the S and D pins to be permuted.
  For more information, see Pin Permutation.
• Exact Parameters requires that the parameter values on the components in a target structure match exactly the parameter values on the components in the clone source. When switched off, Layout XL also reports target structures that have different parameters and values.
  Example
  When switched off, an NMOS device in the source with w = 200 will match an NMOS device with w = 100 in the target.
  If required, you can update the parameters and values to match when you generate a clone by checking the Update Layout Parameters to Match Schematic option in the Generate Clones Form form.
  To prevent any layout-only parameters from getting updated, ensure that the required parameters are set as parameters to be ignored. If any abutment parameters are required for clone generation, they might need to be ignored as well.
  You can set the parameters to be ignored using any of the following methods:
  • Adding the layout-only parameters to the ignore for generation list in CPH.
    See Ignore Parameters and Terminals.
  • Add the layout-only parameters to the Parameters to ignore during generation and update list in the Connectivity form.
    See Parameters.
  • Add the layout-only parameters to the Ignore for generation list in the LAM file.
    See LAM File Mapping Section.
• Exact Connectivity requires that the connectivity of the components in a target structure matches exactly the connectivity of the components in the clone source. When switched off, Layout XL also reports target structures where the set of instances is the same, but they are connected differently.
  Example
  When switched off, two NMOS devices connected by their D and S terminals in the source will match two NMOS devices connected only by their S terminals in the target.
  Searching for non-exact connectivity matches takes significantly longer than searching for exact matches. You can use the options on the Non-Exact Connectivity Matches form to limit the search.

Related Topics

Generate Clones Form

Troubleshoot Cloning

Exact and Non-Exact Matches for Cloning

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