Creating an Abstract from a DEF Block

Abstract Generator can be used to generate abstracts and process antenna information for routed blocks.

1. Choose File – Import – LEF option to import your LEF file.
   
   When generating process antenna data for a routed block, you only need standard cell LEF, which has antenna information on the terminals.
   Ensure that the DEF file contains pins for VSS/VDD with no geometry.
2. Run the Pins step.
   • In the Extract step of Power tab, leave the Extract power nets option off.
   • In the Abstract step of Adjust tab, select the style of power pins that you want to create, for example, boundary or pin.
   
   This solution should work irrespective of the standard cells inside the block having feedthru or abutment pins and no matter what style of power pin you select for the block itself.
   If the DEF file does not contain power pin statements for VSS/VDD, add these statements to the DEF file pins section, as shown below:
   VSS + NET VSS + DIRECTION INOUT + USE GROUND VDD + NET VDD + DIRECTION INOUT + USE POWER
3. Run the Extract step.
   • When calculating the process antenna effect (PAE), it will be necessary to run do_extraction. The recommended way of doing this is to leave the Extract signal nets option off, select all the appropriate antenna calculation buttons on the Antenna tab, and list the polysilicon, contact and diffusion layers in the Layer Assignment for Extraction table. The recommended antenna calculation to be performed here is Calculate hierarchical antenna, which does not require DIFF, CONT, or POLY layers in the extraction.
   • With this set-up, Abstract Generator will do_extraction to generate the PAE data but will not create any new pins. The pin geometry would essentially be the same as defined in the DEF pins section.
4. Run the Abstract step.
   • In the DEF flow, where each pin in the DEF file contained geometry, it is recommended to turn the Create boundary pins option off.
   • For Power Nets, if the power pin geometry was defined in the DEF file, it is likely that this is the desired pin geometry in the abstract. In this case, it is recommended that both Create boundary pins and Create ring pins options be turned off.
   • If the DEF file contains no geometric pin shape, you should select the Create boundary pins option for Signal Nets and Create boundary pins or Create ring pins option for Power Nets.

Related Topics

Import LEF Form