Abstract tutorial

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Procedure for Abstract flow

The tool needs to be invoked from work_cad_scl_180nm folder. Abstract uses "cds.lib" to get the library details. In command prompt, navigate to work_cad_scl_180nm folder and enter the following sequence.

csh
source cadence.cshrc
abstract


Once the gui window comes up, follow the below sequence.

  • Select "file", "library", "open". Select the library which contains the design for which lef needs to be created.
  • The designs are listed in the sub-window "Cell". Select the appropriate design.
  • Select "Flow/Pins". Enter "Map text labels to pins" as "(M1 M1)", which tells the tool that labels in the layout are placed in M1 layer. If required, M2 or other layers can also be added. Enter the output pin names. All other parameters default. Click "run". It shows the pins created for all the ports, input, output and supply.
  • Select "Flow/Extract". Default options for Signal, Power and General. Enable "Antenna parameters" in the Antenna tab if required. Run.
  • Select "Flow/Abstract". Default options. Run.
  • To save the lef file, go to "File", "Export", "Lef". Enter the file name.


Note

  • In the flow, after pins, you can ensure whether the pins are correctly identified by going to "Cells/Terminal properties". You can find a list of pins and direction. In case the direction identified by the tool is not correct, it can be corrected in this section.
  • In the lef file generated, CLASS can be kept as CORE, if the design is a standard cell. It needs to be changed to BLOCK if it is a Macro.
  • Do not modify any figures in the lef file manually, as it alters the pin locations and can result in error later in the flow.