This document describes the design of a CMOS inverter for low power and high speed using Mentor Graphics. It summarizes the following: 1) An inverter was designed using a 25nm technology in Mentor Graphics. Simulations were performed to analyze power dissipation, delay, rise/fall times at different voltages and temperatures. 2) Power dissipation decreased and rise/fall times improved as the supply voltage was reduced from 3V to 1.1V. Delay remained similar across voltage levels. 3) The layout of the inverter was also designed using layout design rules and layout versus schematic checks in Mentor Graphics.

1. Int. Journal of Electrical & Electronics Engg. Vol. 2, Spl. Issue 1 (2015) e-ISSN: 1694-2310 | p-ISSN: 1694-2426
71 NITTTR, Chandigarh EDIT-2015
Design of CMOS Inverter for Low Power and
High Speed using Mentor Graphics
1
Rachna Manchanda, 2
Chanpreet Kaur
1,2
Assistant Professor
1,2
Department of Electronics and Communication, CEC landran
1
Cecm.ece.rm@gmail.com, 2
cecm.ece.ctoor@gmail.com
ABSTRACT:- In parallel with enhancements in the
technology low power consumption have emerged as a
primary design constraint in digital VLSI. This is due to
the increasing demand of portable battery operated
devices in the VLSI circuit design. This really implies a
need to balance ultra low power with area efficient design.
So the only way to minimize energy per operation is to
decrease VDD. The inverter is designed using 25nm
technology in mentor graphics is presented. Further the
designing is followed by the layout of the inverter is done
in this paper.
KEYWORDS: Mentor Graphics, Pyxis Schematic, ELDO,
Pyxis layout, Delay, temperature, Rise time, fall time.
INTRODUCTION
The level of integration keeps on growing more and
more refined as signal processing systems get
implemented on a Very Large Scale Integration (VLSI)
chip. The CMOS technology has emerged as a
predominant technology in the field of nano electronics.
As the technology become compact there is rapid
increase in demand of high performance and also low
power digital systems [1]. These signal processing
applications demands great computation capacity and
consume considerable amounts of energy. While the
performance and the area remain to be two major
design issues, power consumption has become a critical
concern in today’s VLSI system designing. The power
consumption of a design determines how much energy
is consumed per operation and much heat the circuit
dissipates [1].
These above given factors influence a great number of
demanding design decisions, such as the power-supply
capacity, supply-line sizing, packaging, the battery
lifetime and cooling requirements. Digital circuits in
VLSI design have become more advent in recent years
because of its large amount of applications. So there is
need to develop low power design methodologies to
design these circuits.
Propagation delay and power dissipation are two major
issues for the design & synthesis of any VLSI circuits
in this range [2]. Power dissipation limitations come in
two ways. The first is related to cooling applications
when the implementation of high performance systems
is to be done. The high speed circuits dissipate very
large amount of energy in a very short amount of time
and generating a great amount of heat. This heat needs
to be removed by the package on which integrated
circuits are mounted. The second failure of high-power
circuits relates to the increasing popularity of portable
electronic devices. Laptop computers, compact video
players and cellular phones all use batteries as a power
source [3].
To extend the battery life, low power operation is needed in
integrated circuits. This paper briefly presents the concept of
effect of temperature and delay at different voltages at 25
nm technology in mentor graphics.
CHARACTERISTICS OF CMOS
CMOS circuits are made in such a way that all the
PMOS transistors known as pull up networks are always
connected to the voltage source or from another PMOS
transistor. On the same hands all NMOS transistors known
as pull downs are having either an input from ground or
from another NMOS transistor [4]. The PMOS transistor is
designed in such a way that it creates
low resistance between its source and drain contacts, when a
low gate or negative voltage at the gate of the PMOS
transistor and high resistance when a high gate voltage or
positive voltage is applied.
On the other hand, the NMOS transistor creates high
resistance between its source and drain contacts, when a low
gate or negative voltage is applied and low resistance when
a high gate or positive voltage is applied.
CMOS accomplishes the current reduction by
complementing every nMOSFET with a pMOSFET and
connecting both gates and both drains together. A high
voltage on the gates of transistor will cause the nMOSFET
to be in conducting state and the pMOSFET to be in non
conducting state, while a low voltage on the gates causes the
reverse operation. This will reduces the power consumption
and heat generation. Therefore, during the switching time
both MOSFETs will conducts as the gate voltage changes
from one state to another [5]. This induces a spike in power
consumption and becomes a serious issue at high
frequencies.
INTRODUCTION DESIGN STEPS TO MENTOR
GRAPHICS TOOL
The Mentor Graphics HEP2 tools for the flow of the Full
Custom IC design cycle is used. It will run the DRC, LVS
and Parasitic Extraction on all the designs. Initial step is to
create a schematic and attach the technology library called
“TSMC025”.
Other options for choosing the library are also included.
Adding a technology library will ensure that the design can
be done on front to back design. A new cell called
“Inverter” with schematic view is designed a01nd hence
build the inverter schematic by initializing various
components. Once the inverter schematic is done, symbol

2. Int. Journal of Electrical & Electronics Engg. Vol. 2, Spl. Issue 1 (2015) e-ISSN: 1694-2310 | p-ISSN: 1694-2426
NITTTR, Chandigarh EDIT -2015 72
for “Inverter” is generated. Now it will create a new
cell view called “Inverter1”, here it will instantiate
“Inverter” symbol. This circuit is verified by doing
various simulations using ELDO.
In the process EZviewer will show the waveform
window options, waveform calculator, etc... The Pyxis
Layout Editor is based on concentrating the design an
“Inverter” through automatic layout generation, with
completing the other layouts, generating steps, GDSII
file. After that, by taking GDSII file as reference it will
run DRC, LVS checksum the layout, Extract parasitic
and back-annotate them to the simulation environment.
SCHEMATIC OF INVERTER
In this paper, Schematics of inverter are drawn and the
simulations are performed by ELdo simulator in pyxis
Schematic. Eldo provides the most advanced simulation
technology and provides extensive simulation
capabilities.
Fig 2- Schematic view of inverter
Its advanced various analysis can be performed like DC
analysis, transient analysis, DC mismatch, sensitivity,
aging analysis, optimization of parameters, distributed
computing, multi-threading, RC reduction, pole-zero,
Monte-Carlo analysis, distributed computing, S-
parameters, S-domain and Z-domain transfer functions
can be obtained.
Here a 4 pin P-MOS and N- MOS Transistor are used
in pyxis schematic as shown in fig 2. Here VDD is
attached to the P-MOS inverter and ground is attached
to N-MOS inverter.
Fig 3- schematic view of inverter symbol with a pulse input and a DC
source
In fig 3 a symbol is generated of CMOS inverter and a
pulse is applied to the input port of inverter. Pulse is of
3 V and period of pulse is 50ns is set. Similarly a DC
voltage of 1.1 to 3 V is applied to the VDD of inverter.
SIMULATION RESULT
Here are the simulation results of the inverter. Fig 4 is
the DC simulation result of inverter. V(a) shows the
graph of the input to the inverter is starting from zero to
the final value of 3V, and V(y) Shows in below figure
that output is inverted from 3 V to 0V.
Fig 4- DC Simulation result of inverter
Another simulation result is for the transient response of the
inverter both for the input and the output of the inverter as
shown in fig 5. Here it is observed that output of the inverter
is inverted. Here V(y) is the output of the inverter and V (a)
is the input to the inverter.
Fig 5- Simulated output of the inverter
PRACTICAL OBSERVATIONS
Calculation of power dissipation, delay, fall time, rise time
is observed for the Simulation results under 27 degrees
temperature as mentioned in table 1 given below.
Table 1- Various parameters using different VDD
VDD POWER
DISSIPA
TION
DELAY FALL
TIME
RISE
TIME
3V 13.9997P
ATTS
21.165ns 133.36
ps
239.54
ps
1.5V 2.1273P
WATTS
21.310
ns
87.683
ps
181.57
ps
1.3 V 2.8832P
WATTS
21.381
ns
81.790
ps
127.82
ps
1.1 V 2.1273P
WATTS
21.447
ns
63.853
ps
97.420
ps
From the table 1 it is observed that power dissipation of
inverter is reduced as VDD is reduced from 3V to 1.1 V.
Delay is also calculated for various applied voltages. The
fall time and Rise time of output waveform is also reduced
for the when VDD is decreased.
PYXIS LAYOUT FOR INVERTER
The same design of inverter is being implemented on pyxis
layout in mentor graphics as shown if figure 5. Layout is the
fabrication mask of the design for IC manufacturing.
For the low power and high speed inverter design, Layout is
drawn using these following layers - Nwell layer, P

3. Int. Journal of Electrical & Electronics Engg. Vol. 2, Spl. Issue 1 (2015) e-ISSN: 1694-2310 | p-ISSN: 1694-2426
73 NITTTR, Chandigarh EDIT-2015
diffusion, N diffusion, poly silicon, vias, and metal 1
contact.
Fig 5 - Inverter layout on pyxis layout tool
CONCLUSION
The proposed design shows low power, high speed
inverter by using TSMC025 is done. Here the power is
dissipation is less for low voltages as well as fall time,
rise time is also reduced. Further the inverter layout is
also designed using DRC and LVS tools.
REFERENCES
[1] Adil Zaidi, Kapil Garg, Ankit Verma, Ashish Raheja
“Design & Simulation of CMOS Inverter at Nanoscale
beyond 22nm “ in International Journal of Emerging Science
and Engineering (IJESE) ISSN: 2319–6378, Volume-1, Issue-
5, March 2013 ,Pages: 83-87.
[2] Srinivasa Rao.Ijjada, S.V.Sunil Kumar, M. Dinesh Reddy,
Sk.Abdul Rahaman, Dr.V. Malleswara Rao, “DESIGN OF
LOW POWER AND HIGH SPEED INVERTER,” (IJDPS)
Vol.2, No.5, September 2011, pages: 127-134.
[3] Jagannath Samanta, Bishnu Prasad De, Banibrata Bag, Raj
Kumar Maity “Comparative study for delay & power
dissipation of CMOS Inverter in UDSM range “ in
International Journal of Soft Computing and Engineering
(IJSCE) ISSN: 2231-2307, Volume-1, Issue-6, January 2012 ,
pages: 162-167.
[4] K. Roy, S. Mukhopadhyay, H. Mahmoodi-Meimand,
“Leakage Current Mechanisms and Leakage Reduction
Techniques in Deep-Submicrometer CMOS Circuits,”
Proceedings of the IEEE, vol. 91, no. 2, Feb. 2003, pages:
305-327.
[5] CMOS VLSI Design, NEIL H.E. WESTE, IEEE 2006.