Download Abstract: This paper introduces a generalized method for simulating

Applications of OrCAD PSpice software in designing, simulation and analysis of
various applications of Operational Amplifier
Rajender kumar
Sudesh Nandal
SES,BPSMV
Sonipat Haryana
[email protected]
SES,BPSMV
Sonipat Haryana
[email protected]
Abstract-This paper introduces a generalized method for
integrated circuit. The symbol of typical op-amp is
simulating the various applications of operational
shown in fig.1.
amplifier generally termed as op-amps using Orcad
PSpice. Now days engineering education is software
based. The usefulness of this SPICE software in learning
various application of op-amp is enormous than proto
typing practical laboratory. This SPICE software’s
which are important part of engineering education plays
significant role in analyzing and simulating the various
applications of op-amp such as adder, substractor, log &
antilog
amplifier,
differentiator,
integrator,
Fig1. Circuit symbol of op-amps
multivibrator, waveform generators and comparator.
We will present some specific applications of op-amp
It has two input terminal named inverting V- and non
using this software’s in detail which plays a vital role in
inverting terminal V+ and one output terminal Vout.
various field of engineering.
Vs+ and Vs- are power supply terminal. The ideal
Keywords-operational amplifier, Orcad PSpice, SPICE,
operational amplifier characteristics are:
software.
1.
Infinite input impedance
2.
Zero output impedance
I. Introduction
3.
Voltage gain is infinite
Operational amplifier in present-day is the most
4.
Bandwidth is also infinite
widely used electronics device in field of electronic
5.
Slew rate is infinite
systems such as communications systems, medical
6.
Common mode rejection ratio is infinite
electronics, instrumentation, signal processing and
7.
input Offset voltage is zero
performing many mathematical operations such as
But physical op-amp is not ideal. A physical op-amp
addition, subtraction, multiplication, integration and
has large voltage gain, high input impedance and small
differentiations etc. It consists of various stages
output impedance.
namely input stage, intermediate stage gain, level
The block diagram of op-amp is shown in fig 2.
shifting stage and output stage and is fabricated as an
NonInverting
Input
Input
Stage—
Dual Input
Balanced
Output
Amplifier
Intermediate
Stage— Dual
Input
Unbalanced
Output
Amplifier
Output
Stage—
Complementar
y Symmetrical
push-pull
amplifier
Level
Shifting
Stage—
Emitter
Follower
with
Constant
current
source
Inverting
Input
Output
Fig.2 Block Diagram of Operational Amplifier
The IC 741 is widely used general purpose op-amp
frequency-dependent circuits. Characteristics of a
whose circuit symbol is shown in fig 1.The Op-amp
circuit using an op-amp are set by external
can be used in two configurations namely Open loop
components with little dependence on temperature
configuration and closed loop configuration. The open
changes or manufacturing variations in the op-amp
loop configuration is one in which no feedback in any
itself, which makes op-amps popular building blocks
form is fed to the input from the output where as
for circuit design. The various applications of op-amp
closed loop configuration is in which a fraction of
is shown in fig 3.
output is fed back to input. A few limitations of open
OPERATIONA
L AMPLIFIER
APPLICATION
S
loop configurations are: 1. clipping of output
waveform may occur if output voltage exceeds
saturation voltage of op-amp. 2. Open loop gain is not
constant 3. Bandwidth is negligibly small. 4. That why
this
Configuration is not suitable for AC applications but it
finds use in non linear applications such comparators,
Linear
Application
s
Non Linear
Applicatio
nns
Waveform
generator
Voltage
regulator
square wave generator and astable multivibrator. The
closed loop configurations finds its utilization in linear
applications such adder, transconductance amplifier,
instrumentation amplifier, integrator, differentiator,
log and antilog amplifier.
II. Various applications of Op-Amp
Operational amplifiers which have origins in analog
computers, are used in many linear, non-linear and
Scale Changer
Sign Changer
Voltage
Follower
Transconducata
nce Amplifier
Summing
Amplifier
Addersubstractor
Instrumentation
Amplifier
Integrator
Differentiator
Log & antilog
Amplifier
Comparator
and its
applications as
Zero crossing
detector,
Amplitude
distribution
analyzer,
window
detector, and
pulse time
modulator
Schmitt
Trigger
Precision Half
and full wave
rectifier

Sa
mple and Hold
circuits

Cli
ppers
and
Sine wave
generator
Multivibrat
or- Astable,
monostable
Triangular
and saw
tooth wave
generator
Linear
regulator
Single
polarity
and dual
tracking
voltage
regulator
Active
Filter
IV. Introduction of OrCAD PSpice Software
Fig3. Various Applications of Operational Amplifier
III. Simulation of op-amp circuits using OrCAD
PSpice
Computers can be powerful tools if used properly,
especially in the realms of science and engineering.
Software exists for the simulation of operational
amplifier based circuits by computer, and these
programs can be very useful in helping circuit
designers test ideas before actually building real
circuits, saving much time and money. These same
programs can be fantastic aids to the beginning student
of electronics, allowing the exploration of ideas
quickly and easily with no assembly of real circuits
required. Of course, there is no substitute for actually
SPICE which stands for “Simulation Program for
Integrated Circuit Emphasis” is general purpose circuit
program that simulates electronics circuits. It can
perform both basic and advanced analysis like DC
sweep, AC sweep, Transient analysis, noise analysis
and Fourier analysis. It was developed at Berkeley in
University of California, USA. There are three
platforms shown by figure 4(a-b) for PSpice which
depends on SPICE version are as follows:
1. PSpice A/D or OrCAD PSpice A/D (Version 9.1 or
above)
2. Pspice Schematics (Version 9.1 and below)
3. OrCAD Capture lite( Version 9.2 & above)
building and testing real circuits, but computer
simulations certainly assist in the learning process by
allowing the student to experiment with changes and
see the effects they have on circuits. Throughout the
practical session and beyond classroom, we would be
incorporating
computer
printouts
from
circuit
simulation frequently in order to illustrate important
concepts. By observing the results of a computer
simulation, a student can gain an intuitive grasp of
circuit behavior without the intimidation of abstract
mathematical analysis. To simulate various circuits
involving op-amps on computer, we make use of
different spice software’s like Orcad PSpice, Aim
Spice, LTSpice and B2Spice.Both LTSpice and
PSPICE are used professionally, and are based on the
open source SPICE3 engine, which was developed at
the University of California, Berkeley and serves as a
foundation for electronic simulation. Simulating a
circuit involves creating the circuit by placing parts
and connecting with wires, running the simulation for
the circuit, and then analyzing the results. In this paper
we are present three different applications of op-amps
which are simulated using OrCAD PSpice software.
Fig. 4(a-b) Different platforms for PSpice
In PSpice A/D, circuit is described by statements and
Analysis descriptions
analysis commands which is called a circuit file. The
.TRAN 1us 400us ; analysis commands
platform for OrCAD Capture lite is similar to Pspice
Output descriptions
Schematics but with more advance features. In SPICE,
.PRINT TRAN V(3) I(R1) ; output commands
A circuit is described to a computer by using
.PROBE ; Graphical wave analyser
CIRCUIT FILE which contains circuit details of
.end [end of circuit file]
components and elements, sources and commands for
After writing the circuit file, it is run on PSpice A/D
analysis descriptions and the way in which output is to
platform; the simulated output is shown in figure 7.
be presented. A circuit file format for RLC circuit
5 Design, analysis and Simulation and Discussion
whose pulse response is to be calculated shown by
The first circuit which we have design, analyses and
figure 5 which can be read by SPICE is as follows:
simulated is lossy integrator which is shown in fig.
6(a). The integrator is circuit which provides an output
1
R1
2
2
V1 = -200v
V2 = 200v
TD = 0
TR = 1ns
TF = 1ns
PW = 100us
PER = 200us
voltage proportional to the time integral of the input as
3
L1
50uH
V1
given by equation 1.
C1
1
10uF
Vout =R1Cf
 Vidt --- Eq. 1
If the input signal is as a square wave, then output will
0
be a triangular wave as shown by fig. 5(b) as per eq.1.
Pulse response
of RLC Circuit
C1
10ns
R2
100k
V2
2
-
OS2
10k
OUT
3
Vin
+
V-
V1 = -1
V2 = 1
TD = 0
0
15v
7
U33
V+
R1
OS1
5
R3
6
1
1k
R4
4
uA741
TR = 0
TF = 0
PW = 0.1ms
PER = 0.2ms
V3
1k
0
LOSSY
INTEGRATOR
CIRCUIT
15v
0
Fig.5 PSpice Schematics for writing circuit file and its simulated
Pulse response.
Title __ Pulse response of RLC Circuit
Circuit Descriptions
V1 1 0 pulse (-200 200 0 1ns 1ns 100us 200us)
R1 1 2 2
L1 2 3 50uH
C1 3 0 10uF
Fig. 6(a-b) PSpice Schematics of lossy integrator and
its input and output waveform with OrCAD PSpice.
The 2nd application of op-amps is waveform generator.
performance parameters such as bandwidth, resonant
Using op-amps, we can generate square wave and
frequency etc. of this filter can be determined by
triangular waveform with single circuit shown by 7(a)
resistor R1 and two capacitor C2 and C3 using
and its output is shown by 7(b).
following equations.
R2
SQUARE AND TRIANGULAR
WAVEFORM CIRCUIT
39k
Vp
0
B=
7
OS2
12k
-
V-
OUT
2
OS1
5
R
6
1
0
OS2
OUT
2
68k
+
-
V-
+
OS1
0.1591
---Eq. 2
RC
5
C3
6
R2
0.015uF
1
uA741
42.42k
4
3
3
V+
U35
V+
U36
R1
7
15v
4
uA741
0
Vp
Vn
C2
21.21k
0.015uF
U37
2
-
V+
R1
0
C
7
15v
OS2
OUT
3
+
V-
Vin
1Vac
0Vdc
OS1
5
6
1
uA741
4
0.012uF
0
15v
Vn
0
15v
0
0
Narrowband band
pass filter
Fig. 7(a-b) PSpice Schematics of square and triangular
and its input and output waveform with OrCAD
PSpice
Fig. 8(a-b) PSpice Schematics narrowband band pass filter and its
input and output waveform with OrCAD PSpice
The third and final applications which we will design,
Conclusion
analyses and simulate using OrCAD PSpice is
This paper mainly discusses the various applications
narrowband band pass filter. Here we are taking the
of 741 operation amplifier and their simulations using
case of narrowband band pass filter shown in fig. 8(a)
OrCAD PSpice software. We can design, simulate and
and its frequency response is by fig 8(b). The
verify any of applications with required parameters.
Because of graphical facilities of OrCAD PSpice, it is
useful in enhancing the understanding of various
applications of op-amps. We can also use different
spice software like LT spice, Top Spice and Spice
Opus for better understanding of various applications
and compare the results with theoretically calculated
result.
REFERENCES:
[1] Boylestad R., L. Nashelsky, 1992. Electronics
Devices and Circuit Theory, Prentice-Hall Inc.
[2] PSPICE A/D online manual
[3] National Semiconductor Company, National
Operational Amplifier databook, 1995
[4] Rashid M.H. Microelectronics Circuit Analysis
and Design, PWS Publishing Co, 1999
[5] Rashid M.H., Introduction to PSpice Using
OrCAD
for
Circuits
and
electronics,
Pearson
Education., 2006
[6] Gayakwad, R.A, Op-amps and Linear integrated
circuits, Prentice-Hall India, 2000.