1ECE 249 Lab 1Spring 2005Adapted from“Short Tutorial on Cadence”, Z. Tao and M. Keramat, UCSN-0300-ZBT-03, March 2000“Symbol Creation of Sub-Circuits in Cadence,” Z. Tao and M. Keramat, UCSN-0700-ZBT-10, July 20001Cadence Software Fundamentals1 IntroductionThis lab aims at introducting you to the Cadence software on the Sun workstation. First, a list ofbasic UNIX commands is given, and then followed by setting the UNIX environment for the Cadencedesign tools. Finally, a simple example of simulating a CMOS Inverter is presented.2 Basic Unix CommandsSome basic UNIX commands that you need to know are listed in Table I.Table I. Basic Unix commandsList the files in the current directory: LsDisplays the name of the files in the directory. ls –lDisplays additional information (eg. permissions)about the files in the directory. ls –aDisplays all files in the directory, includinghidden files. ls –alCombines the previous two options.Change (or move between) directories: cd <directory>Moves to the directory specified by directory cd ..Moves up a directory - two periods represent theparent directory. cd ~Moves to your home directory – tilde representsyour home directory.Make a new directory: mkdir <directory>Makes a new directory called directoryDisplay the (path of the) current directory you are in: pwdDisplays the name of the current directory you arein.Copy a file or directory:2 cp <existing file> <newfile>Creates a new file identical to existingfile butwith the name newfile cp -R <existing Dir> <newDir>Creates a new directory identical to existingDirbut with the name newDirRename or move a file: mv <oldfile> <newfile>Renames oldfile to newfile within the samedirectory. mv <oldfile> <directory/newfile>Moves oldfile to a different directory withthe name of newfileRemove (delete) a file: rm <file>Deletes file. The file cannot be recovered.Change password: yppasswdChange current password.3 Setting up an Account to Run the Cadence ToolsYou need to login a UNIX workstation and set up your UNIX environment to run the Cadencesoftware. Depending on when your account was created, you may be using csh as your default loginshell. The current recommended shell for ECS users is bash. To check if you are using, type “echo$shell” at the shell prompt. If the reply is “/bin/csh”, you will need to change to use the bash shellby typing “exec bash” at the shell prompt. Once you have established that you are using bash,proceed with the following steps to setup the Cadence tools.Step 1:> mkdir cadenceStep 2:> mkdir cadence/modelsStep 3:> mkdir inboxStep 4: The following command will overwrite your .bashrc file in your home directory. If youhave something important in your .bashrc file, save it to a temporary copy.> bash /apps/ecs-apps/software/ece/cdssetup/cdsupdate2005Add in your .bashrc changes if necessary.Step 5:> source .bashrc4 Starting Cadence SoftwareStep 1: > cd ~/cadence (current directory must be cadence)3Step 2: > icfb &A Command Interface Window (CIW) window appears on the screen, shown in Fig. 1.Fig. 1. Main window of Cadence tools.5 Creating Inverter SchematicStep 1: In the CIW window, go to File… New… LibraryA New Library window appears. Fill out the pop-up form according to Fig. 2, and click OK.Fig. 2. Creating a new library.Step 2: In the CIW window, go to File… New… CellviewA Create New File window appears, in Fig. 3. Fill it out and click OK.4Fig. 3. Creating a new file.Then a new Virtuoso Schematic Editing window appears as in Fig. 4.Fig. 4. The Virtuoso Schematic Editing window.5Step 3: In the Virtuoso Schematic Editing window, go to Add…  Instance …An Add Instance window will appear. Click Browse, and a Library Browser window appearsas shown in Fig. 5.6Fig. 5. Instance window.7Step 4: Select ami05Lib in Library, pmos4 in Cell, and symbol in View. The Add instance windowshould now have the pmos information filled in as in Fig. 6. Stamp a pmos device symbol inthe Virtuoso Schematic Editing window, as shown in Fig. 7.Fig. 6. Add instance window.8Fig. 7. Stamping pmos device.Step 5: Repeat step 3–4, but adding an nmos4 transistor.Step 6: In the Virtuoso Schematic Editing window, go to Add…  Pin. Name the pin ‘A’.Step 7: Repeat step 11 for a pin named ‘B’.Step 8: Repeat step 11 for a pin named ‘vdd’.Step 9: Repeat step 11 for a pin named ‘gnd’.Step 10: In the Virtuoso Schematic Editing window, go to Add…  Wire and connect the instancesas shown in Fig. 8.9Fig. 8. Inverter schematicStep 11: In the Virtuoso Schematic Editing window, go to Design…  Check and Save. You shouldhave no errors or warnings.6 Symbol Creation of Sub-Circuits in CadenceIf a design is complicated, generally we use the top-down design method, or hierarchy structure. Inthis case, it is very beneficial to assign each sub-circuit a corresponding symbol (or icon) to representthat module. This step largely simplifies the schematic representation of the overall design. Thus, the“symbol” view of a circuit module is an icon that stands for the collection of all components within themodule.Step 1: In the Virtuoso Schematic Editing window, go to Design…  Create Cellview  FromCellview, the following window will pop up.10Fig. 9. “Cellview From Cellview” form.Step 2: Check the view names and click OK. Make sure that the target view name is symbol, which isindicated in “To View Name”.Step 3: In a new window, a symbol is automatically generated. The default shape of the symbol iconis a rectangle as shown in Figure 10.11Fig. 10. Automatically generated inverter symbol.Step 4: Editing the shape of the symbol icon. You can do the following operations on your symbol:(1) Deleting/replacing some existing parts(2) Adding new geometric shapes(3) Changing the locations for pins and instance name(4) Adding new labelsFigure 11 is an example for a manually created inverter symbol, which was obtained byediting the symbol shown in Fig. 10.12Fig. 11. The inverter symbol after modification.Step 5: In “Virtuoso Symbol Editing” window, go to Design…  Check and Save. Thus, you havecreated your own symbol for future use.7 SimulationNow we are going to simulate the inverter we just created to confirm that it operates as we expect.Step 1: In the CIW window, go to File… New… CellviewA Create New File window appears, in Fig. 12. Fill it out and click OK.13Fig. 12. Creating a new file.Then a new