18-525

Cadence Tools Lab Manual

CADENCE TOOLS BASICS:

TOPICS:
STARTING AND STOPPING CADENCE
LIBRARY MANAGER
CREATING LIBRARIES
CELLS AND VIEWS
CREATING NEW CELLS
OPENING FILES



STARTING AND STOPPING CADENCE [TOP]

To run any of the Cadence tools run the following commands:

  1. cd ~/cds
  2. icms &
The Cadence Command Information (CIW) Window will open. This window allows you to access all of your Cadence files and to start all of the Cadence tools.
 
 


 Command Information Window

IMPORTANT: To quit working in Cadence, you MUST:

  1. Close all Cadence windows except the CIW window by selecting Window...Close or File...Quit from the window menu.

  2. Do NOT close the windows using the Xwindow option available on the frame of each window!
  3. Only when all other windows have been closed:

  4. Close the CIW window by selecting File...Exit from the menu.

LIBRARY MANAGER [TOP]

Libraries are organizational units that contain the various gates, schematics, and other design units that you will be working with. The Library Manager tool is used to manage libraries. To start it, select Tools...Library Manager in the Log Window.  The Library Manager window will open.


Library Manager Window

The Library Manager Window shows the libraries that  are available to you. You will use the ece322 library for all of the labs. Components will be added to the ece322 library as needed for your labs and projects. The ece322 library is based on the HP.35u library, which is also listed in the Library Manager Window. The basic library contains pins and other primitives and the cdsDefTechLib library is placeholder for other internal Cadence functions.

You will only be using components from the ece 322 library and any libraries that you create yourself. You should create a new library for each of your labs and projects.


CREATING LIBRARIES [TOP]

  1. Select File...New...Library from the Library Manager menu. The New Library window will open:

Library Manager
  1. Enter the name of the library you wish to create in the name box.

  2.  
  3. Make sure the directory is <your home directory>/cds/cdslib and that No DM is selected in the Design Manager frame.

  4. In the example shown, a library named lab1 is being created in the directory /home/blevine/cds/cdslib. (Note: The home directory is /home/blevine; your home directories will look like /afs/ece/usr/blevine.)
     
  5. Click OK.

  6.  
  7. In the Technology File for New Library window that will open, select either Attach to an existing techfile or Don't need a techfile as instructed in the specific lab, and click OK.





CELLS AND VIEWS [TOP]

Cadence libraries contain components, such as gates and transistors. Each component is called a cell. A cell can have multiple cell views. These cell views represent different ways that the component can be represented. For example, a NMOS transistor can be represented as a symbol to be used in a schematic, as a simple switch level Verilog behavioral model, or as an analog SPICE model. In the example below, the Library Manager tool is used to show all of the cell views for the cell called nfet in the ece322 library. There is currently a symbol view and a verilog view. Views can be added to cells, just as cells can be added to libraries.  Understanding this hierarchical structure is important to avoid confusion when using the Cadence tools.


CREATING NEW CELLS [TOP]

To create a new cell (component in your library), you actually create a view for the cell. To create a new cell:
 

  1. Select File...New...Cell View from the Library Manager menu or to the Cadence Information Window menu. The Create New FIle window will open:


  1. Select the name of the library you wish to add your cell to in the Library Name list.

  2.  
  3. Enter a name for the cell in the Cell Name box.

  4.  
  5. Different Cadence tools are used to create different types of Cell Views. Choose the tool you will use to create the cell from the Tool list according to the instructions you are given in the specific lab. The View Name box will be automatically filled in based on your choice in the Tool list. In the example above, the Composer - Schematic tool is selected, and Schematic  was automatically filled placed the View Name field.

  6.  
  7. Verify that the Library path file is <your home directory>/cds/cds.lib.

  8.  
  9. Click OK.



OPENING FILES [TOP]
 

  1. To open an existing file, got to the Command information Window and select File...Open from the menu. The Open File window will appear.



  1. FIrst you must specify the library by selecting it from the Library Name list.  A list of the cells in that library will appear in the Cell Names box. You can choose the cell by selecting it from the list or by typing the name in the Call Name box.

  2.  
  3. Once you have selected the cell, you can choose the view you wish to work with by selecting it from the View Name list. Only those views available for the cell you have selected will appear in this list.

  4.  
  5. The default mode for opening the cell view is Edit mode, but you can select Read instead, if you wish to open a read-only copy.

  6.  
  7. Click OK. The cell view you select will open in the appropriate tools for that view. (i.e., Composer for schematics, Virtuoso for layouts, etc.)

 


© 1999 Carnegie Mellon University