Cadence Tutorial

Cadence Tutorial
VLSI EE IITK
NIKHIL/MTECH EE/IITK/15104075
To start Cadence
• Right click on desktop
• Click on open terminal and enter the following
commands
• mkdir ~/cadence_designs (If not created already)

• cd ~/cadence_designs (Change to Work Directory)
• csh (Change to C shell)
• source /cad/cadence/IC/5141.csh (Source the Script)
• icfb &
Cadence GUI will open
Initially the screen will look like
• Click on File
• Then New → Library
• Provide a file name
• In the Technology File section, select Attach to an existing techfile
• To create a new cell view under a library, click on File
• Then New → Cellview
• Select a library
• Provide a Cell Name
After opening the CMOS_INVERTOR cell view following window will be opened.
Go to left side of window a symbol of add instance will appear left click on that
symbol.
A new window shown as follows will pop up, left click on Browse and proceed.
When we browse window will appear as shown –
left click on --1)UMC_18_CMOSMos(category)N_18_MM(cell)symbol.
And click on close (left corner)
After closing previous window you will see following window.
You can Name NMOS as M0 and can change W and L of NMOS then click on Hide(left upper
corner). You can see YELLOW coloured NMOS symbol. By left click you can place it anywhere on
black screen.
Similarly you can add PMOS_18_MM
as shown
Now to connect wire at pin you can again go to left panel of screen where click on
symbol as shown below which is Wire(narrow).
And connect the two transistors as shown by just clicking the point which we want join
and stretching it up to second point.
Now it time to add voltages
follow the steps Add instance  analogLib  Sources  Independent  vdc
symbol.
Now in this window assign the DC voltage as1.8(Max UMC_180_MM Voltage ) and
click on Hide.
Follow the same procedure to add gnd
Add instance  analogLib  Globals gnd  symbol.
Now to add Input voltage as square wave-
Add instance  Independent  vpulse  symbol.
Assign the values as follows –
Name VIN
Voltage 10 V
Voltage 2 1.8 V
Pulse width0.5u (type u after 0.5)
Period 1u
Now the circuit will look like as
Now name the wires as input and output by clicking on symbol shown as follows and
selecting the wire after typing desired name in window which is shown on next page
Type Input and click on desired wire which we want to name as input.
Similarly add the name to output name as Output as shown .
Now out schematic is complete.
Click on check and save symbol as shown which will shoe 0 errors and 1 warning as we
have left 1 pin open (output pin).
Transient Analysis
CMOS INVERTOR
For transient analysis go to left upper corner and click on Tool Analog Environment
A new window by name Analog environment will pop up.
Now in this window click on Analysis  Choose … a new window will open .
Select on trans and assign Stop time as 10us and Don’t forget to select to Enabled .
Now for plotting the output click on Outputs  To Be Plotted
After that Select on Schematic
After clicking on Select on Schematic left Click on Input and Output.
After this Input and Output name will appear in Analog Design Environment window as shown .
Now click on symbol Run(Right bottom corner of Analog window ) to Simulate
the circuit
Following window will appear.(RESULT)
To separate the input and output click on strip chart symbol of graph window.
DC ANALYSIS
OF CMOS INVERTOR
First remove the pulse input and connect the
vdc from analogLib as input to CMOS as shown
in next page
Now follow 
First open Analog Design Environment window
Now click on outputs  To Be Plotted Select on Schematic.
And select on input and output pin as shown then Output and input signal will apper
in ADE as shown.
Choose Analyses select dc select Save Dc Operating Point
Then Sweep Variable select  Component Parameter and click on  Select
Component…Then click on source which we are going to vary i.e. Vdc (input).
Now on clicking the source a new window will open click on dc vdc and click ok
that will add the parameter name in Parameter Name block in Choose analysis
window.
Now sweep Range –
 select Start-Stop  assign start=0 V and stop =1.8V
Make sweep type  linear
Number of steps 100 and click OK
And click on Run Symbol of Analog Design Environment window .
And The RESULT
COMPONENT DISPLAY
By using Differential Amplifier
For this we have to design Differential Amplifier We consider the design parameter as
follows
1)UMC_180_NM Technology
2)Vdd=1.8V(fixed for UMC_180_NM)
3)Av=100(40dB)
4)Input Common Mode Range(-)=0.8
5))Input Common Mode Range(+)=1.6
6)CL=10pf
7)Slew Rate=5V/usec
8)GBP=5MHz
Schematic of Differential Amplifier
For design of differential amplifier you can refer standard textbook t
I have calculated the values as follows:
All values are approximate
upCox =60uA/v2, unCox =300uA/v2
Vtn = 400mV, Vtp=500mV
( for all transistor L= 1um)
I0=50uA
(W/L)1,2=7
(W/L)5,8=9
(W/L)3,4=84
CL=10pF
And design the Differential amplifier as shown in previous amplifier
All transistor have L=1um
Towards component Display in CADENCE
• First carry out DC analysis
Goto  Results  Annotate  DC operating point
By doing this Vds ,Vgs and Id of all transistor will display along with transistor
Vds ,Vgs and Id get displayed
Now to see other DC parameter of All transistors go to Results Print DC operating
Points
Result Display window as shown will get pop up. Now by clicking mouse on
transistor you will see all parameter of transistor in Result Display
Window(Next Page)
Now move that window in Mid of display
You can See various parameter by scrolling side bar of Result display window
such as gm, gmb, gds, and various capacitances
And by scrolling down you can see one of the most important information of about transistor i.
e. region which shows region of operation of transistor
In cadence
0- Cut off, 1-Linear,2-Saturation,3-Sub threshold region
AC ANALYSIS
• For Ac analysis we will design the two stage
op-amp with following specification-
Vdd=1.8V
DC gain=1000(60dB)
GBW=30MHz
PM=60 degree(open loop)
ICMR(+)=1.6V
ICMR(-)=0.8V
CL=2pf
Lmin=0.5um(for all Transistors)
Schematic of Two stage op-amp(Take L=0.5um for all transistor)
Vdd=1.8
Make the schematic design as follows
Now for AC analysis Design the input as shown and give small ac sign to positive
terminal as shown
Now goto  Tools Analog Design Environment  Analyses  choose ac analyses
Sweep Variable select Frequency
select start-stop Start=1Hz and Stop=100MHZ
click ok or apply
Now Run the Simulation
Go to Results  Direct Plot Ac Gain & Phase and left click the Ac Gain & Phase
After that minimize the analog Desig environment window and Click on Output(that
will change the colour) and after that without clicking anywhere else click on In_Pos
Then Bode plot of input and Output will get plotted (Next Page)
That’s the Bode plot or ac analyses
By going into the graph window and adding marker to see unity gain frequency and Phase lag at
Unity gain frequency you can see the values
{GBP=24.75MHz(desired=30MHz)}
{PM=180+Phase angle=180-115=65*(Desired=60*) }
`
• By tuning the values of W/L of required transistor we can get out desired values of
Design.
THANK YOU
Prepared By NIKHIL BASVESHWAR KASTURE(Y15 BATCH RF AND MICROWAVE)

Cadence Tutorial

Uploaded by

Copyright:

Available Formats

Cadence Tutorial

Uploaded by

Document Information

Original Description:

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Cadence Tutorial

Uploaded by

Copyright:

Available Formats

Cadence Tutorial

• mkdir ~/cadence_designs (If not created already)

• First carry out DC analysis

Prepared By NIKHIL BASVESHWAR KASTURE(Y15 BATCH RF AND MICROWAVE)

You might also like