Loading the Virtual Machine
After installing VMWare, Open it and choose file>>Open. Browse for the directory
“CentOS” (The folder you extracted from the file “ELC411.rar”.) Then choose the file “CentOS.vmx” and press “Open”. A similar window will appear.
Choose “Edit virtual machine settings” and adjust the hardware allocated to this VM depending on your computer (Optional).
Choose “Power on this machine”. It will ask you if you have copied or moved this machine, choose I moved it. It is ok if you’ve ch osen I copied it.
The Linux will start to load, It will ask you about the username and password, use this info: o
Username: root
o
Password: elc411
Starting Cadence (the design tool)
Right-click on an empty space on the Linux desktop. Choose “Open Terminal”, then type
“cadence”. DO NOT CLOSE THIS TERMINAL or the cadence will close also!
The program will load and you will have something like this:
o
CIW (icfb) window: This is used to link all the cadence tools that we will use. If any error or warning occurs inside any t ool, it will be printed in this window.
o
Library Manager: This window will be used to manage design files. If this window does not appear, you can open it from the icfb window through Tools>>Library Manger.
In cadence, each design must be inside a library, e ach library can have one or more category, each category can contain one or more cell, which is the basic design unit. Each cell can have more than one view (we will only use schematic and symbol views for now.)
It is important to organize your design files. I suggest that each member in the group should have a library with his name. Inside the library you should create different categories like: logic, opamps, test_benches, etc. Inside each category you can put your designs or your test_benches.
The Inverter Example
First we need to create a library. From “Library Manger” choose File>>new>>library. And do as shown in this figure(name the library by your name):
Choose the library “your Name”, then choose file>> new>>category, name it “logic” and press OK. (press show categories in the “ library manger” window if it is not chosen)
Choose File>>new>>cell view. Type “inverter” for t he cell name, and choose “composerschematic” as the tool.
A new window called “Virtuoso Schematic Editing” will open.
To put the cell “inverter” in the category “logic”, go back to the “Library Manager” and right-click on the category “logic”, choose “Modify”. Do as shown in the following figure.
Now we need to draw the schematic of an inverter. From the “Virtuoso” window press ‘i’ to insert a device.( small ‘i’ is different from capital ‘I’) A new window will appear, do as shown:
After you choose to add the symbol of an nmos1v, click on the “Virtuoso” window and insert the symbol of the NMOS transistor. Hit “Escape” button from the keyboard to exit the insert mode. Redo for a PMOS transistor and choose the devise “pmos1v”. You should have something similar to this:
To edit the properties of the NMOS and PMOS devices (i.e. the width and length, etc.), choose the NMOS and press ‘q’ from your keyboard. The following dialogue box will appear:
The technology we use is TSMC 130nm. This means that the minimum length of a transistor is 130nm (for 1v transistors only). The minimum width for this transistor is
150nm. We need to make ( ) ≅
2( ) , so edit the PMOS to have a
width of 300nm and a length of 130nm.
Now we need to do the wiring, press ‘w’ and connect the transistors as shown:
We need now to add the I/O ports, press ‘p’ and do as shown in the next figure. Then
press the ‘Escape’ button. Insert 3 more ports: out (direction: output), vdd and gnd(direction: inputOuput).
You should have something similar to this:
Now save the design by pressing the “Save & Check” button as shown. If there is any error or warning, check them from the icfb window and fix them.
Now that we finished the schematic of the inverte r we need to create a symbol for it. Do as shown in the following figure.
A new window will appear. Now edit the drawing (optional) to look like an inverter. You should get something similar to this:
Now if you look at the “Library Manager” you will see the cell “inverter” has now 2 views: a schematic and a symbol.
Now we need to simulate the inverter. One way to do it is to create a new cell view of
type “composer-schematic” from the “Library Manager” and name it “inverter_tb” inside a category named “test_bench” for example.
Inside the insert the following devices: (similar to what we’ve do ne to insert an NMOS) o
An inverter from the library “your_name>>logic>>inverter>>symbol”
o
A DC source from the library “analogLib>>sources>>independent>>vdc>>symbol” Edit it to make its DC value = 1.2v (using keyboard button ‘q’)
o
A square-wave source from the library
“analogLib>>sources>>independent>>vpulse>>symbol” Make its V1=0V, V2=1.2V, period = 100 u. o
Since the output of the inverter will be floating you need to add an
“unconnected net” connector from the library “basic>>misc>>noConn>>symbol”
Label the input and output of the inverter by pressing the key ‘l’ and typing the label you want then pressing on the net (or wire) you need to label)
Note that if you have two different nets with the same name they will be considered one net even if they are not physically connected. You can use this property to simplify the wiring in complex designs.
Now you should have something like this:
Click on “Save & Check” and fix any er ror or warning.
Simulating the circuit
To simulate the circuit we need to open “Anal og Environment” (ADE) from tools menu. A similar window will appear:
We need to run a transient simulation, the following figure shows how to setup a transient simulation.
To run the simulation press “Netlist and run” button.
To plot outputs, you can either: o
Add outputs to the output list from the menu “Output>>To be ploted>> Select on Schematic” and select the nets you want to plot from the schematic. Then press the plot button from the ADE window.
o
Use the main form tool from “Results>>Direct Plot>>Main Form”, choose the options you like (or keep the defaults) then select the nets you want from the schematic they will be directly plotted. Note the main form tool has different options for different simulations: transient, DC,etc.
Plot the Input vs. the output, you should get similar curves:
