Multimedia Tutorial on Operational Amplifiers, Fundamentals,
and Applications
David Báez-López, Franz Sol Sánchez, and Guillermo Espinosa Flores Verdad*
Departamento de Ingeniería Electrónica
Universidad de las Américas-Puebla
Cholula, Puebla 72820
*Coordinación de Electrónica
Instituto Nacional de Astrofisica, Optica y Electronica
Tonantzintla, Puebla
MEXICO
e-mail: d.baez@ieee.org
Abstract - This paper presents a multimedia tutorial to
learn operational amplifier fundamentals. This tutorial is
aimed at the practicing engineer who needs to recall the
theory for a quick op-amp circuit design and at the student
which has never studied op-amps and needs a quick
introduction to the topic. The tutorial is multimedia
displaying pictures and circuit diagrams including oral
explanations to speed up the learning procedure. This
tutorial package is written in Visual Basic 3.0. The authors
have found student response very satisfactory, especially in
those students with little or no prior knowledge of the
topic.
I. Introduction
Operational Amplifiers (Op-amps) are a basic building block
in many linear and non linear signal processing operations.
Therefore, electrical engineers must know the basics of
them, going from circuits based on op-amps modelled
ideally to circuits with op-amps using more realistic non
ideal models. Unfortunately, many electrical engineering
undergraduate curricula do not have a full course devoted to
teaching op-amp circuits. There are many reasons that
account for this fact. The number of topics to teach at the
undergraduate level has increased considerably during the
last several years. Thus, educators have to squeeze or leave
out some topics. This is the case with op-amps, which are
now taught within the linear electronics course. This means
that no more than four weeks ( or 12 hour classes) within the
course and within the curriculum are dedicated to op-amps.
Thus, a need arises to have some other ways to learn op-amp
theory and circuit applications, such as self learning or
conference tutorials. This paper presents a computer based
tutorial on op-amps whose main goal is to provide users
with the basics on op-amps as well as on circuits using opamps. The tutorial is bilingual using either English or
Spanish depending upon user requests. The tutorial has the
following features:
1) It is multimedia based incorporating audio and video
within the tutorial.
2) It is bilingual having a choice of either English or
Spanish
3) It contains oral explanations of the topics
II. Operational Amplifiers
One of the most used electronic devices nowadays in linear
and nonlinear signal processing applications is the
operational amplifier [1-4]. There are several reasons that
account for this fact, among which we can mention a low
cost, simple rules for design, and availability as an off-theshelf component. In addition, design engineers can build
quite sophisticated designs without paying attention to the
internal working of the operational amplifier. Operational
amplifiers (op-amps) were developed first by George
Philbrick when he was an employee for the National Defense
Research Council (NDRC) in the early 1940's. He later
founded his own company and developed the first op-amp
using vacuum tubes. At the time the name operational
referred to the mathematical operations that were performed
with op-amp based circuits, such as summation, integration,
solution of simultaneous equations, etc. Analog computers
were based almost completely in op-amps. The advent of the
digital computer did not affect the applications of op-amp
circuits in almost any area of analog linear and non-linear
electronics. It is in 1962 that Burr-Brown Corp and
Philbrick Research Inc. develop separately the first integrated
op-amps, and from this year on, there is available in the
market a great deal of IC op-amps with different
characteristics. Nowadays, the IC op-amp is considered a
"workhorse" of linear systems. The first IC op-amp
commercially available was the µA702 produced by
Fairchild Semiconductor in 1963. In spite several
disadvantages, it was the best op-amp of its time. The
following development was the µA709 introduced by
Fairchild in 1965. This circuit was the first to use a dual
power supply, if had a low input current and a larger dc gain.
The first internally compensated op-amp was introduced by
Fairchild in 1968 with the µA741 [2]. These IC op-amps
revolutionized some areas in electronics due to their reduced
design time, because instead of designing amplifiers from
dozens of components, circuit designers developed their
circuits around a few standard, commercially available
prepackaged operational amplifiers.
Feedback techniques are used to suppress non ideal
properties of op-amps so that individual variations in
particular amplifiers have negligible effect on final circuit
performance. Hence, circuit designs based on op-amps
usually have highly predictable performance. Moreover,
today's op-amps are highly reliable, and circuit designers can
expect that production copies of their final systems will
closely emulate the performance of the prototype and will
require a minimum of initial debugging and little long-term
maintenance. Currently, areas where op-amps are used
include; instrumentation, control systems, audio, interfaces,
A/D and D/A converters, signal processing, power
electronics,
industrial
electronics,
bioelectronics,
telecommunications, and so on.
III. Tutorial
The tutorial covers the main topics on op-amps. These main
topics covers only some applications of op-amps. This is so
because there is a great deal of applications available for op-
amps. Interested and more advance readers can consult some
of the references. The tutorial was designed using tools to
have a multimedia environment. The tools used were the
following:
- Visual Basic Helpwriter. To produce hypertext documents
for windows. (version 1.9.2)
- Paintbrush. To produce the pictures and circuit drawings.
- Microsoft Visual Basic. To create easily multimedia
presentations with good quality.
- Sound'Le. To insert audio in the tutorial (.WAV format)
- Ware Studio and Ensemble CD. Tools to digitize audio.
The tutorial can be accessed either in English or in Spanish
depending upon user's choice.
The tutorial starts by showing a welcome window as shown
in Fig. 1. This window has a bar for exit, help, language,
sound, and monitors (to select the appropriate display).
The C icon shows the menu with the topics in the tutorial.
The S icon shows a summary of the most important topics
in the tutorial.
Fig. 1 Main window for the tutorial
In this window, students can choose the language for the
tutorial. The two buttons "C" and "S" have been described
before.
When the C button is clicked, a subwindow is displayed at
the right-hand upper corner in the screen ( see Fig. 2). This
window displays all the chapters available in the tutorial.
The chapters are:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Op-amp history
How to identify an op-amp
Circuit connection with op-amps
Op-amp terminals
Basic configurations
Op-amp applications
Op-amp characteristics
Linear applications
Non linear applications
A brief description of each chapter follows.
1.
Op-Amp History
In this chapter, it is mentioned G. Philbrich as the inventor
of the first op-amp. Also, the work of Burr-Brown Research
Corp. is described. The first IC op-amps are mentioned as
well as a description of their characteristics is given.
Advantages and disadvantages of op-amps are described.
difference amplifier are shown in some detail here. These
circuits are shown in Fig 6. A detailed analysis of them is
given. Any student can follow the analysis presented. An
improved version of the difference amplifier is shown in Fig.
7.
Fig. 2. Window showing chapters available for reading. The
number 3 indicates to the user which chapter he is reading
currently.
Fig. 3 Layout for the 741 op-amp
2. How to identify an op-amp
This chapter describes how an IC op-amp is encapsulated.
Pictorials showing the different cases are shown. Pin
diagrams for the archipopular µA741 can be seen. Also a
brief description of the code letters for the manufacturers of
op-amps is shown. Temperature code and suffix are also
explained. Fig. 3 shows the microphotograph for the 741 opamp and Fig. 4 shows the most popular casings for opamps.
3. Circuit connections with op-amps
How to power an op-amp is described in this chapter. A set
of suggestions can be accessed to avoid failure when using
op-amps. A set of not-to-do things is also included.
4. Op-amps terminals
Pin description for the popular µA741 op-amp are given.
The ideal characteristics of an op-amp are explained ( see
Fig. 5).
5. Basic Configurations
The three basic op-amp configurations, namely, the
inverting amplifiers, the non-inverting amplifier, and the
Fig. 4 Casings for op-amps.
6. Op-amp Applications
Some general applications of op-amps are given. These
include a triangular to sine wave converter, a sine to
triangular converter, voltage to current converter, power
amplifier, triangular wave generator, and oscillator with
quadratic output. The list of applications is intended to
provide an idea of how many circuits can be designed with
op-amps and it is not by any means exhaustive.
rectifier. Detailed analysis are shown for these circuits (see
Figs. 9 and 10).
IV. Hardware and Software Requirements
7. Op-amp characteristics
This chapter explains some of the main characteristics of opamps such as
-dc characteristics
-input and output impedance
-offset voltage
-offset current
-bias input current
-ac characteristics
-bandwidth
-slew rate
-noise
-and some performance limitations.
Minimum hardware requirements are a 486 multimedia
computer, SVGA monitor with at least 16K colors, 8 MB
RAM, and 30 MB hard disk space. The multimedia
computer is a requirement to be able to hear the oral
Fig. 6 Some basic configurations.
Fig. 5 Pin description for general and for the 741 op-amp.
8. Linear applications
Some linear applications of op-amps are described here.
These applications include the integrator amplifier, the
differentiator amplifier, instrumentation amplifier, active
filters, a history of filter realizations, types of filters and
several topologies for active filters are shown.
9. Non linear applications
Some non linear applications are given, these include
comparators, log amplifiers, antilog amplifiers, and half wave
Fig. 7 Improved difference amplifier.
(a)
Fig. 8 Rectifier circuit.
explanations of the lesson. The 16K colors are needed for a
better display of the images of the tutorial.
V. Conclusions
We have presented a multimedia tutorial package on
Operational Amplifiers. This tutorial can be used by
students and by practicing engineers. We have found that
users with little or no knowledge on op-amps can benefit by
learning more on the topic. This tutorial runs on any PC
IBM compatible 486 or better.
(b)
Fig 10 Non linear applications, (a) Power amplifier,
(b)Comparator
References
Acknowledgements
The authors acknowledge the partial support of Instituto de
Investigación y Posgrado of the Universidad de las
Américas-Puebla and Consejo Nacional de Ciencia y
Tecnología México under grant 3848.
1.
2.
3.
4.
Fig. 9 Log amplifier
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National Semiconductor Linear Databook, Sunnyvale,
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J.V. Wait, L. P. Huelsman, and G.A. Korn,
Introduction to Operational Amplifiers, Mc Graw-Hill
Book Co., New York, 1975.
R. F. Coughlin and F. F. Driscoll, operational
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