Schematic Entry with Composer
At this point, you should have setup files in your working directory for runnung CADENCE with NCSU CDK.
Otherwise, refer to Setting up Unix Envrionment. We will build the lowest level library cell, Inverter for example.


Design entry through schematic capture:

To start CADENCE, type icfb& in the command and you should get a window with CIW(Command Interface Window) as Figure 1.

CIW
Figure 1. CIW



We will use the NCSU CDK which automatically starts the library manager and you should see NCSU* libraries and cdsDefTechLib similar to Figure 2.

Library Maanger
Figure 2. Library Manager



Creating a new library:

1. Select File --> New --> Library in Library manager.
2. Enter a library name and choose Compile tech library   option exactly according to Figure 3.


creating library  
Figure 3. Creating a library



3. Click OK. Now, your library manager should show new library, EE525 in this particular case as in Figure 4.


library manager  
Figure 4. Library manager with EE525 library



Creating a new schematic:

1. Select File --> New --> Cell view   in library manager and choose library under which you would like  to create the new cell view.
2. Enter a cell view name and choose Composer-Schematic as the tool . View name should be schematic exactly according to Figure 5.

Creating a new cell view
Figure 5. Creating a new cell view



3. Click OK. A blank composer-schematic window should open.


Placing instances on schematic:

To draw the inverter, you need to add PMOS, NMOS transistor, GND, power supply, pins for input and output, and wire it together.
To add components to your schematic,

1. From Composer-Schematic menu, select Add --> Instance This brings out Add instance form with Component browser which is for NCSU CDK like in Figure 6.


browsing for componentsadding an istance
Figure 6. Browsing for components and Adding an instance



2.  To select transistors, click on N_Transistors for the nmos and P_Transistors for the pmos4. You should have Add instance window like in Figure 7.

  
Getting an nmos device   Getting an pmos4 device
Figure 7. Getting  nmos and pmos4 device



3. Repeat step 2 to get vdd and gnd with click on Supply_Nets in component  browser. The components in Supply_Nets are actually global signals. The pins  for global 
    signals are automatically given. If you make a mistake and need to get out of add instance mode, just press the Esc key.
    So far, you should have schematic as Figure 8.

   
major simbol of cmos inverter
Figure 8. Creating CMOS inverter



Connecting wires with pins:

After the instances are created and placed, you can connect them by wires to form the inverter. To add wires,

1. From Composer-Schematic menu, select Add --> Wire (narrow)
2. Click left mouse button on the starting point, and click left mouse button on as many transition points as you want. Then if you want to end wire, just double click.

After wiring, you need to create pins for input and output nodes. In order to do this,

3. From Composer-Schematic menu, select Add --> Pin...   An Add Pin form appears.
4. Type in "A Y" as pin names, and make sure the Direction is "input" as shown Figure 9.


Add pins
Figure 9. Add Pins



5. Move cursor to schematic window. Then, click left mouse button to place pin "A".
6. Move cursor back to Add Pin form, change "Direction " to "output". Then, repeat step 5.
7. Final schematic view of inverter will be similar as Figure 10.
8. Don't forget to save by selecting Design --> Check and Save in Composer-Schematic menu.


completed schematic
Figure 10. Completed schematic









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