Importing and Exporting CIF and GDS Files

Importing files

• Step 1:  Destination Library and Technology File.
Cadence requires that you have a both 1) a design library that will store the imported file and 2) a technology file/library, which defines the layers.  The design library and the technology library can be the same library, or they can be different libraries.
 
• WARNING!  If you import a file into an existing library, you might overwrite existing designs.  If any cell in the GDS or CIF file has the same name as a cell in the destination library, Cadence will overwrite the existing cell with the imported cell.  Cadence will not warn you.  I fouled up a circuit layout once because of this.  I strongly encourage you to always create a new library, in one of the following ways, before you import a file.  This is your only warning.

 
• Start Cadence

Two windows will appear.  One is the CIW (Command Interpreter Window, I believe).  The other is the Library Manager.
 
• If you don't have a technology file or library, you need to create a new one:

CIW -> Technology File -> New..
Technology Library Name: your_library_name
Load Existing Technology File: cdsDefTechLib
(You can choose a different existing technology file if you want, but cdsDefTechLib is recommended if you are going to create a completely new technology.)

At this point, I believe that you have to quit and restart Cadence in order to be able to use your new technology library.  Please let me know if you find a better way.
 

• If you already have a technology file, but you want to create a new destination library:

Library Manager -> File -> New
Library Name: your_library_name
Attach to an Existing techfile
Attach to Technology Library: your_existing_library_name

• Step 2: Import File
• If you are importing a GDS file

CIW -> File -> Import -> stream
 
• If you are importing a CIF file

CIW -> File -> Import -> CIF
 
• In the "Stream In" or "CIF In" window

Input File: your_input_file_name.gds (or .cif)
Library name: your_library_name
 
• If you are using an existing technology file for which you do not have write permission:

Click "Options"
Check "Skip Undefined Layer Purpose Pair"
 
• If you have a layer map file:

Click "User-Defined Data"
Layer Map Table: your_layer_map_file

Click here for more info about layer map files.
 

• Once PIPO STRMIN completes successfully, you need to refresh the library manager

Library Manager -> View -> Refresh
 
• PIPO STRMIN can fail for a variety of reasons.  A few possibilities are:
1. You just created a new technology file.  In this case, restart Cadence as mentioned above.
2. You don't have write permission for the technology file that you are using.  In this case, select "Skip Undefined Layer Purpose Pair" as mentioned above.
3. Standard reasons, such as wrong file name or wrong directory, etc.

• Step 3: Open the Imported Layout

• Step 4: Edit Layer Appearance

If your imported file has layers that were not previously included in your technology file, or if you created a new technology file, you might want to edit the color and stipple pattern of the layers.  There are two approaches:
 
• Edit your display resources file (DRF)

Advantage: This might be the easier of the two methods.
Disadvantage: Since your DRF is unique, other users won't see the same layer colors unless they copy your DRF.  If you are sharing layouts, this can be a problem.
CIW -> Tools -> Display Resources -> Editor
Application: Virtuoso
Tech Lib Name: your_library_name
Layers: LSW

Select a layer and edit the color and pattern as you desire.

File -> Save
If you call the file display.drf and save it in your Cadence start directory (e.g. ~/cadence/display.drf), it will automatically load whenever you start Cadence.  Otherwise, you will have to load it yourself (File -> Load) later on.
 

• Edit your technology file

Advantage: You don't have to keep track of which display.drf file. you are using
Disadvantage: It is more tedious to change the layer appearance.

CIW -> Technology File -> Edit Layers
Technology Library: your_library_name

Select a layer and click "Edit"

To change the color and stipple pattern, choose a different display packet under the Display Resources heading (e.g. METAL, goldX, ...)

To edit another layer, unselect the current layer in the "Layer Purpose Pair Editor" window, and select the next layer.  A selected layer is surrounded by a thin box.  It can be quite difficult to see if a layer is selected.
 

• Additional notes about importing:
• If you import a gds file to an existing technology file, Cadence converts the gds layer numbers to layer names according to the Cadence layer number, defined in the tech file.  In contrast, when exporting to a gds file, Cadence converts layers to gds numbers according to the stream number, defined in the tech file.

• Step 1: Export File
• If you are exporting a GDS file

CIW -> File -> Export -> stream
 
• If you are exporting a CIF file

CIW -> File -> Export -> CIF
 
• In the "Stream Out" or "CIF Out" window

Library Name: your_library_name
Top Cell Name: your_export_cell_name
View Name: layout
Output: Stream DB   -or-  CIF DB
Output File: your_output_file_name.gds (or .cif)

The following settings convert the layout to a micron scale (i.e. 1.0 in the layout equals 1micron in the exported file).

Scale UU/DBU: 0.001
Units: micron

 
• If you have a layer map file:

Click "User-Defined Data"
Layer Map Table: your_layer_map_file

Click here for more info about layer map files.

Send comments/suggestions/questions to cadence@bsac.