Magic - Design Rule Checking using Mentor Calibre (via Cadence Virtuoso)

Cadence and Magic use different file formats for the storage of design data.
Interchange is possible via a common GDS2 stream format.

Procedure

• go to magic directory e.g.

    hind2<~>$ cd ~/design/magic/c35b4/cell_lib
  

• translate magic file to cadence format

    hind2<~/design/magic/c35b4/cell_lib>$ do_c35b4_cellin <cellname>
  

  cell cellname (in file cellname.mag) and all sub-cells will be translated.

The Magic layout editor supports simple on-line DRC.
The Cadence Virtuso layout editor supports the Mentor Calibre DRC post-processor.

Magic designs must pass the more stringent Calibre DRC before they will be accepted for fabrication.

Procedure

• Change to directory containing cadence files

    hind2<~/design/magic/c35b4/cell_lib>$ cd ~/design/cadence/c35b4/cell_lib
  

• Start cadence virtuoso via the ams_cds script

    hind2<~/design/cadence/c35b4/cell_lib>$ ams_cds -tech c35b4
  

  ams_cds is a wrapper script supplied by Austria Micro Systems (AMS) which sets up the design environment and then calls the cadence virtuoso tool. It is part of the AMS 'HIT-Kit' design kit.

• Use the library manager for library, cell and cellview manipulation

    Tools -> Library Manager...
  

  Within the library browser the left hand mouse button is used for navigating around the library structure while the right hand mouse button provides access to the commands used to manipulate the libraries, cells and cellviews.

  • Open the imported design for edit

    Use the mouse to select Library: cell_lib, Cell: <cellname> and View: layout then invoke the open command -

      File -> Open...
    

• Run the Calibre DRC

    Calibre -> RUN nmDRC
  

  in the first of two Calibre windows select the runset file

      Load Runset File
        Runset File Path [ calibre_dir/drc.runset       ]
      OK
  

  from the second Calibre window invoke the DRC

      Calibre Interative - nmDRC
        Run DRC
  

• View the results

  Calibre is very fussy, you will undoubtably have some errors.

  If you select the errors from the Calibre DRC : RVE window, you will get a text description of the error in the bottom pane of the window and information about the location of the error in the right hand pane. More usefully, the Cadence Virtuoso layout window will jump to view the highlighted error.

• While some errors may be rectified by post processing of the designs (e.g. dummy metal generation to overcome "density" problems), others will require you to modify your original magic design

Note that when you are learning how to use this DRC facility, it is best to check a magic design created with known errors. You can then track down the same errors using Calibre DRC.

All Cadence and Mentor documentation is available on-line.

For Cadence documentation use the help menu on the Virtuoso layout editor window:

  Help -> Virtuoso Documentation Library

For Calibre documentation use the help menu on the Calibre Interactive window:

  Help -> Help and Manuals

Full Design Rules for the AMS c35b4 process are also available via the Design Rule Documents web page.