Create Schematics

 

At this point, you have created a library of your own and can begin the design process. 

 

1.     To create a schematic, click on the File -> New -> Cell view in the Library Manager Window. A pop-up window will appear.

2. You can choose Cell name as inverter in this lab section. If you click OK, You will see Schematic Editing window as shown below

 

 

You need to bring devices into your design in this window.  The following figure is what you are aiming for.

 

 

 

3.     To place instances (devices), type i on your schematic window. You will see 2 windows (Component Browser and Add Instance) as shown in figure below.

 

For example, in order to design a inverter, we need two transistors (nmos and pmos). In case of the nmos, choose NCSU_Analog_Parts -> N_Transistors in the Component Brower. And then, select nmos4 (four terminal NFET) as follows:

Add Instance window will be changed to following window.

This window will allow you to change the sizes (Width, Length and Fingers) of the transistor you want. To place the instance, click on the left mouse button. Another new instance will immediatedly become ready to be placed. If you need an additional nmos, you can re-click the left button in your schematic window. Press ESC to stop adding anymore nmos devices. 

 

To change the properties of the instance that you just placed, click on top of the device and type q.  An object properties editing form will pop up.

 

You can also choose pmos4 in the NCSU_Analog_Parts library for pmos.

 

4.     To place a wire connecting the two devices, type w and click on the left mouse button on top of the location you want. Press ESC to stop adding wire.

 

 

5. The next step is to specify pins of inverter. In the Schematic Editor window, type p and pop-up will appear.

We will specify all pins name as shown in table below. Then move your cursor into the schematic window on the wire where you like to place the pin (you should see the pin in yellow outline).  Click on the left mouse button to place the pin.

 

 

Pin Names

Direction

Input node

Vin (or any other name)

Input (inputoutput)

Output node

Vout (or any other name)

Output (inputoutput)

VDD node

VDD

inputoutput

GND node

GND

inputoutput

 

 

 

 

QUICK USAGE REFERENCE:

1.     Press 'p' to add pins

2.     Press 'q' on the device/instance to edit properties for the device

3.     Press 'w' to add wires

4.     Press 'f' to fit the schematic in your schematic window.

5.     Press 'l' to label a wire.

6.     Press 'm' to move an object

7.     Press 'DEL' key to delete an object

8.      Press 'Up' and 'Down' arrows to move up and down within a schematic window.

9.     Press 'ESC' to terminate any of the operations in the schematic window.