Analog Integrated Circuits Design
Lab1: Virtuoso Introduction
Lecturer: Prof. Robert Bogdan Staszewski
Guest Lecturer: Viet Nguyen (viet.nguyen@ucdconnect.ie)
TAs:
Sayan Kumar (sayan.kumar@ucdconnect.ie)
Feifan Hong(feifan.hong@ucdconnect.ie)
1
Introduction
• This tutorial gives a quick refresher of Lab0 and then extends further
to have more simulations on Inverter.
• Please take the seats where you did your first lab. Please conduct the
lab with the same lab-mate with whom you share the cadence ID.
• Please alternate usage of cadence between you and your lab mate, so
that both can learn equally.
2
LAB0 Refresher
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Log in to Windows in Room 329
Open FastX
Implement the connection
The accounts will be assigned to you in the beginning of the session
Open a terminal (Right Click -> Open Terminals)
Entering the folder of the design: type create_work_area AIC_2022 TSMC18 GP
and press [enter]
• This step is only done once for the entire lab sessions. In the future, you just need to enter the design folder AIC_2021
• Entering the folder of the design: type cd AIC_2022
• Setup the tools: type setup_tools and press [enter]
• Open virtuoso: type virtuoso & and press [enter]
3
Creating a Library
• The Command Interpreter Window (CIW)
is the first window that appears.
• A library is where you create the cells.
Each cell can have different views. For this
tutorial, you’re going to create an inverter
cell with two views: schematic and
symbol.
• During the semester, you can create a
new library for each of your lab sessions
and the final project.
4
Open Library Manager
• Open the library manager you will see
your library is already there
Example of the Library manager
5
Creating a Cell View
• For the next step, you should create a cell
inside the library that you’ve already
created.
• In the library manager Click on the library
name then choose File -> New -> Cellview.
• The Schematic window will open.
6
Creating the Schematic
Shortcut: type “i”
7
Creating the Schematic
• You could see the different libraries in
the Library Browser window.
• Libraries containing user-defined cells
are called design libraries (Lab1).
• Libraries containing technology-specific
components are called reference
libraries.
• tsmc18: transistors for TSMC180 Tech
• analogLib: Capacitors, resistors and sources
8
Creating the Schematic
• After choosing the component, you need
to edit its properties.
• For the nmos and pmos, you could
change the size, number of fingers and
multiplier.
• If you need to change the properties of a
component after inserting it, you could
click on it and then type “q”. The same
window would appear.
9
Creating the Schematic
• Add the remaining symbols to complete
the inverter schematic.
• The transistors and other technologyspecific components will always be
selected from tsmc18 library.
• Generic symbols such as capacitors,
resistors, vdd, gnd and voltage and
current sources will be selected from the
analogLib library.
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Creating the Schematic
• You also need to add pins to the
schematic.
• Keep in mind to change the direction for
input (IN), output (OUT) and
inputoutput (vdd and gnd).
11
Creating the Symbol From the Schematic
• At this point, we could create a symbol from the inverter schematic.
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Creating the Symbol From the Schematic
• Here, you could change the pin
specifications. You’ve already created
pins in the schematic and now you could
decide the placement of the pins.
• The pin names should be the same as
what already exist in the schematic.
13
Creating the Symbol From the Schematic
• After creating the symbol,
press save and then you
could close the window.
14
Circuit Simulation
• You will use the Spectre circuit simulator via the Cadence Analogue
Environment to do the DC, Transient and AC analysis of the inverter.
• You will create different cells as the testbenches.
15
Transient Analysis
• Create a new cell called
TestBench_Transient
• Type “i” to add a new instance.
• In the Library Browser, choose the
inverter symbol from the Lab1
library.
• This is the inverter that you created
earlier.
16
Transient Analysis
• Add the remaining
components as the figure
shows.
• All the components could be
found in the analogLib library.
17
Transient Analysis
• You will use a vpulse as the voltage source
for the transient analysis.
• By clicking on the vpulse and typing “q”, you
could change the source properties.
• Fill it as you see in the figure and click OK.
• Make sure to click “save” after you made all
the changes in the schematic.
18
Transient Analysis
• Go to:
Launch > ADE L
• Click on the button shown in the
figure.
19
Transient Analysis
• First choose the dc
analysis and select
the : “Save DC
Operating Point”
and click OK.
• Open the analysis
window again and
choose “tran” and
for the Stop Time
type in 20u. Click
OK.
20
Transient Analysis
• Click on the play button to start the
simulation.
• A new window will open which
shows the status of the simulation
and contains possible errors and
warnings.
21
Transient Analysis
• In the ADE window, Go to:
Results > Direct Plot >
Main Form
• In the “Direct Plot Form”
window choose “voltage”.
• By clicking on different
nets on the schematic, you
could show the signals.
• Plot the “Vout” and “Vin”
vs. “time”.
22
AC Analysis & DC Sweep
• Create a new cell called
TestBench_AC
• Create the schematic shown in
the figure.
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AC Analysis & DC Sweep
• You will use a vsin as the voltage source for
the AC analysis and the DC sweep.
• By clicking on the vsin and typing “q”, you
could change the source properties.
• Fill it as you see in the figure.
• You can use variables as well as constants
for parameters. Type Vdc for the DC Voltage
parameter.
• Make sure to click “save” after you made all
the changes to the schematic.
24
AC Analysis & DC Sweep
• After saving the schematic, go to:
Launch > ADE L
• In the ADE L window, go to:
Variables > Copy From Cellview
• In the Design Variables box, you could see
“Vdc” which were earlier defined in the vsin
parameters. Type “0.9” as its value.
25
AC Analysis & DC Sweep
• Set up the DC and AC analysis as you
did for the Transient analysis.
• This time, you will do a DC sweep.
Choose “Vdc” as the variable and fill
the rest as shown in the figure.
26
AC Analysis & DC Sweep
• Click on the play button in the ADE window.
• In the ADE window, Go to:
Results > Direct Plot > Main Form
• In the “Direct Plot Form” window choose
“dc” as the analysis and “voltage” as
function.
• By clicking on different nets on the
schematic, you could show the signals.
• Plot the “Vout” and “Vin” vs. “Vdc”.
27
AC Analysis & DC Sweep
• In the ADE window, Go to:
Results > Direct Plot > Main Form
• In the “Direct Plot Form” window choose
“ac” as the analysis and “voltage” as
function and “magnitude” as the modifier.
• By clicking on different nets on the
schematic, you could show the signals.
• Plot the “Vout” vs. “frequency”.
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