Electronic devices (conventional current version) (9th edition) by thomas l floyd

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E LECTRONIC
D EVICES
Conventional Current Version
Ninth Edition

Thomas L. Floyd

Prentice Hall
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Library of Congress Cataloging-in-Publication Data
Floyd, Thomas L.
Electronic devices : conventional current version / Thomas L. Floyd.— 9th ed.
p. cm.
Includes index.
ISBN-13: 978-0-13-254986-8 (alk. paper)
ISBN-10: 0-13-254986-7 (alk. paper)
1. Electronic apparatus and appliances. 2. Solid state electronics. I. Title.
TK7870.F52 2012
621.381—dc22

2010043462

10 9 8 7 6 5 4 3 2 1

ISBN 10:
0-13-254986-7
ISBN 13: 978-0-13-254986-8


P REFACE

This ninth edition of Electronic Devices reflects changes recommended by users and
reviewers. Applications and troubleshooting coverage have been expanded to include
several new topics related to renewable energy and automated test programming. As in the
previous edition, Chapters 1 through 11 are essentially devoted to discrete devices and
circuits. Chapters 12 through 17 primarily cover linear integrated circuits. A completely
new Chapter 18 covers an introduction to programming for device testing. It can be used as
a “floating” chapter and introduced in conjunction with any of the troubleshooting
sections. Chapter 19, which was Chapter 18 in the last edition, is an online chapter that
covers electronic communications. Multisim® files in versions 10 and 11 are now available
at the companion website, www.pearsonhighered.com/electronics.

New in This Edition
Reorganizations of Chapters 1 and 2 These chapters have been significantly reworked for a more effective coverage of the introduction to electronics and diodes. New
topics such as the quantum model of the atom have been added.
GreenTech Applications This new feature appears after each of the first six chapters
and introduces the application of electronics to solar energy and wind energy. A significant
effort is being made to create renewable and sustainable energy sources to offset, and
eventually replace, fossil fuels. Today’s electronics technician should have some familiarity
with these relatively new technologies. The coverage in this text provides a starting point

for those who may pursue a career in the renewable energy field.
Basic Programming Concepts for Automated Testing A totally new chapter by Gary
Snyder covers the basics of programming used for the automated testing of electronic
devices. It has become increasingly important for electronic technicians, particularly those
working in certain environments such as production testing, to have a fundamental grounding in automated testing that involves programming. This chapter is intended to be used in
conjunction with the traditional troubleshooting sections and can be introduced or omitted
at the instructor’s discretion.
More Multisim® Circuits Updated to Newest Versions Additional Multisim® circuit
files have been added to this edition. All the files have been updated to versions 10 and 11.
New Format for Section Objectives The section objectives have been rewritten to provide a better indication of the coverage in each section. The new format better reflects the
topics covered and their hierarchy.
Miscellaneous Improvements An expanded and updated coverage of LEDs includes
high-intensity LEDs, which are becoming widely used in many areas such as residential
lighting, automotive lighting, traffic signals, and informational signs. Also, the topic of
quantum dots is discussed, and more emphasis is given to MOSFETs, particularly in
switching power supplies.


IV

◆

P REFACE

Standard Features
◆

Full-color format.

◆

Chapter openers include a chapter outline, chapter objectives, introduction, key
terms list, Application Activity preview, and website reference.

◆

Introduction and objectives for each section within a chapter.

◆

Large selection of worked-out examples set off in a graphic box. Each example has a
related problem for which the answer can be found at www.pearsonhighered.com/
electronics.

◆

Multisim® circuit files for selected examples, troubleshooting, and selected problems are on the companion website.

◆

Section checkup questions are at the end of each section within a chapter. Answers
can be found at www.pearsonhighered.com/electronics.

◆

Troubleshooting sections in many chapters.

◆

An Application Activity is at the end of most chapters.

◆

A Programmable Analog Technology feature is at the end of selected chapters.

◆

A sectionalized chapter summary, key term glossary, and formula list at the end of
each chapter.

◆

True/false quiz, circuit-action quiz, self-test, and categorized problem set with basic
and advanced problems at the end of each chapter.

◆

Appendix with answers to odd-numbered problems, glossary, and index are at the
end of the book.

◆

PowerPoint® slides, developed by Dave Buchla, are available online. These innovative, interactive slides are coordinated with each text chapter and are an excellent
tool to supplement classroom presentations.

Student Resources
Companion Website (www.pearsonhighered.com/floyd) This website offers students
an online study guide that they can check for conceptual understanding of key topics.
Also included on the website are the following: Chapter 19, “Electronic Communications
Systems and Devices,” a table of standard resistor values, derivatives of selected equations, a discussion of circuit simulation using Multisim and NI ELVIS, and an

examination of National Instruments’ LabVIEWTM. The LabVIEW software is an example of a visual programming application and relates to new Chapter 18. Answers to
Section Checkups, Related Problems for Examples, True/False Quizzes, CircuitAction Quizzes, and Self-Tests are found on this website.
Multisim® These online files include simulation circuits in Multisim® 10 and 11 for
selected examples, troubleshooting sections, and selected problems in the text. These
circuits were created for use with Multisim® software. Multisim® is widely regarded as
an excellent circuit simulation tool for classroom and laboratory learning. However, no
part of your textbook is dependent upon the Multisim® software or provided files.
Laboratory Exercises for Electronic Devices, Ninth Edition, by Dave Buchla and Steve
Wetterling. ISBN: 0-13-25419-5.

Instructor Resources
To access supplementary materials online, instructors need to request an instructor access code.
Go to www.pearsonhighered.com/irc to register for an instructor access code. Within 48 hours
of registering, you will receive a confirming e-mail including an instructor access code. Once
you have received your code, locate your text in the online catalog and click on the Instructor
Resources button on the left side of the catalog product page. Select a supplement, and a login


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P REFACE

page will appear. Once you have logged in, you can access instructor material for all Prentice
Hall textbooks. If you have any difficulties accessing the site or downloading a supplement,
please contact Customer Service at .
Online Instructor’s Resource Manual Includes solutions to chapter problems,
Application Activity results, summary of Multisim® circuit files, and a test item file.
Solutions to the lab manual are also included.
Online Course Support If your program is offering your electronics course in a distance learning format, please contact your local Pearson sales representative for a list of
product solutions.
Online PowerPoint® Slides This innovative, interactive PowerPoint slide presentation

for each chapter in the book provides an effective supplement to classroom lectures.
Online TestGen This is a test bank of over 800 questions.

Chapter Features
Chapter Opener Each chapter begins with an opening page, as shown in Figure P–1. The
chapter opener includes a chapter introduction, a list of chapter sections, chapter objectives,
key terms, an Application Activity preview, and a website reference for associated study aids.
ᮤ

Chapter outline

2

D IODES

CHAPTER OUTLINE

List of
performancebased chapter
objectives

2–1
2–2
2–3
2–4
2–5
2–6
2–7
2–8
2–9

2–10

◆
◆
◆
◆
◆
◆
◆
◆

AND

A PPLICATIONS

VISIT THE COMPANION WEBSITE

Diode Operation
Voltage-Current (V-I) Characteristics of a Diode
Diode Models
Half-Wave Rectifiers
Full-Wave Rectifiers
Power Supply Filters and Regulators
Diode Limiters and Clampers
Voltage Multipliers
The Diode Datasheet
Troubleshooting
Application Activity
GreenTech Application 2: Solar Power

CHAPTER OBJECTIVES
◆

◆

Use a diode in common applications
Analyze the voltage-current (V-I) characteristic of a diode
Explain how the three diode models differ
Explain and analyze the operation of half-wave rectifiers
Explain and analyze the operation of full-wave rectifiers
Explain and analyze power supply filters and regulators
Explain and analyze the operation of diode limiters and
clampers
Explain and analyze the operation of diode voltage
multipliers
Interpret and use diode datasheets
Troubleshoot diodes and power supply circuits

Study aids and Multisim files for this chapter are available at
/>
Website
reference

INTRODUCTION

In Chapter 1, you learned that many semiconductor devices
are based on the pn junction. In this chapter, the operation
and characteristics of the diode are covered. Also, three
diode models representing three levels of approximation are
presented and testing is discussed. The importance of the

diode in electronic circuits cannot be overemphasized. Its
ability to conduct current in one direction while blocking
current in the other direction is essential to the operation of
many types of circuits. One circuit in particular is the ac
rectifier, which is covered in this chapter. Other important
applications are circuits such as diode limiters, diode
clampers, and diode voltage multipliers. A datasheet is
discussed for specific diodes.

Introduction

APPLICATION ACTIVITY PREVIEW

You have the responsibility for the final design and testing
of a power supply circuit that your company plans to use in
several of its products. You will apply your knowledge of
diode circuits to the Application Activity at the end of the
chapter.

Application
Activity
preview

KEY TERMS
◆
◆
◆
◆
◆
◆

Key terms

F I G U R E P– 1

A typical chapter opener.

◆
◆
◆

Diode
Bias
Forward bias
Reverse bias

◆

V-I characteristic
DC power supply

◆

Rectifier
Filter
Regulator

◆

◆

◆
◆
◆
◆
◆

Half-wave rectifier
Peak inverse voltage (PIV)
Full-wave rectifier
Ripple voltage
Line regulation
Load regulation
Limiter
Clamper
Troubleshooting

Section Opener Each section in a chapter begins with a brief introduction and section
objectives. An example is shown in Figure P–2.
Section Checkup Each section in a chapter ends with a list of questions that focus on the
main concepts presented in the section. This feature is also illustrated in Figure P–2. The
answers to the Section Checkups can be found at www.pearsonhighered.com/electronics.
Troubleshooting Sections Many chapters include a troubleshooting section that relates
to the topics covered in the chapter and that illustrates troubleshooting procedures and
techniques. The Troubleshooting section also provides Multisim® Troubleshooting exercises. A reference to the optional Chapter 18 (Basic Programming Concepts for
Automated Testing) is included in each Troubleshooting section.

◆

V

VI

ᮣ

◆

P REFACE

FI G URE P–2

A typical section opener and section
review.

Section checkup
ends each
section.

482

FET A MPLIFIERS

◆

AND

S WITCHING C IRCUITS

results in conduction power losses lower than with BJTs. Power MOSFETs are used for
motor control, dc-to-ac conversion, dc-to-dc conversion, load switching, and other applications that require high current and precise digital control.

SECTION 9–6
CHECKUP

Introductory
paragraph begins
each section.

9–7

1. Describe a basic CMOS inverter.
2. What type of 2-input digital CMOS circuit has a low output only when both inputs are
high?
3. What type of 2-input digital CMOS circuit has a high output only when both inputs
are low?

T ROUBLESHOOTING
A technician who understands the basics of circuit operation and who can, if necessary,
perform basic analysis on a given circuit is much more valuable than one who is limited
to carrying out routine test procedures. In this section, you will see how to test a circuit
board that has only a schematic with no specified test procedure or voltage levels. In
this case, basic knowledge of how the circuit operates and the ability to do a quick
circuit analysis are useful.

Performance-based
section objectives

After completing this section, you should be able to
❏
❏

Reference to Chapter
18, “Basic
Programming
Concepts for
Automated Testing”

Troubleshoot FET amplifiers
Troubleshoot a two-stage common-source amplifier
◆ Explain each step in the troubleshooting procedure
◆ Relate the circuit board to the schematic

◆

Use a datasheet

Chapter 18: Basic Programming Concepts for Automated Testing
Selected sections from Chapter 18 may be introduced as part of this troubleshooting
coverage or, optionally, the entire Chapter 18 may be covered later or not at all.

A Two-Stage Common-Source Amplifier
Assume that you are given a circuit board containing an audio amplifier and told simply
that it is not working properly. The circuit is a two-stage CS JFET amplifier, as shown in
Figure 9–46.

ᮣ

FIGURE 9–46

+12 V

A two-stage CS JFET amplifier circuit.

R2
1.5 k⍀

R5
1.5 k⍀

C3

C5
Vout

C1

0.1 μ F

Q1

Vin

10 μ F

Q2

0.1 μ F
R1
10 M⍀

R4
10 M⍀

C2
100 μ F

R3
240 ⍀

R6
240 ⍀

C4
100 μ F

Worked Examples, Related Problems, and Multisim® Exercises Numerous workedout examples throughout each chapter illustrate and clarify basic concepts or specific procedures.
Each example ends with a Related Problem that reinforces or expands on the example by
requiring the student to work through a problem similar to the example. Selected examples
feature a Multisim® exercise keyed to a file on the companion website that contains the
circuit illustrated in the example. A typical example with a Related Problem and a
Multisim® exercise are shown in Figure P–3. Answers to Related Problems can be found at
www.pearsonhighered.com/electronics.
ᮣ

FI G URE P–3
T HE C OMMON -S OURCE A MPLIFIER

A typical example with a related
problem and Multisim® exercise.

◆

463

The circuit in Figure 9–14 uses voltage-divider bias to achieve a VGS above threshold.
The general dc analysis proceeds as follows using the E-MOSFET characteristic equation
(Equation 8–4) to solve for ID.
VGS = a

R2
bV
R1 + R2 DD

ID = K(VGS - VGS(th))2
VDS = VDD - IDRD

Examples are set off from
text.

The voltage gain expression is the same as for the JFET and D-MOSFET circuits. The ac
input resistance is
Equation 9–5

Rin ‫ ؍‬R1 || R2 || RIN(gate)
where RIN(gate) = VGS>IGSS.

EXAMPLE 9–8

ᮣ

A common-source amplifier using an E-MOSFET is shown in Figure 9–17. Find VGS, ID,
VDS, and the ac output voltage. Assume that for this particular device, ID(on) = 200 mA
at VGS = 4 V, VGS(th) = 2 V, and gm = 23 mS. Vin = 25 mV.

FIGURE 9–17

VDD
+15 V

Each example contains a
related problem relevant
to the example.

R1
4.7 M⍀

C1

RD
3.3 k⍀

C2

Vout

10 μ F

Vin
0.01 μ F

Solution

R2
820 k⍀

VGS = a

RL
33 k⍀

R2
820 kỈ
bV
= a
b 15 V = 2.23 V
R1 + R2 DD
5.52 MỈ

For VGS ϭ 4 V,
K =

Selected examples include a
Multisim® exercise coordinated
with the Multisim circuit files
on the companion website.

ID(on)
(VGS - VGS(th))2

=

200 mA
= 50 mA>V2
(4 V - 2 V)2

Therefore,
ID = K(VGS - VGS(th)) = (50 mA>V 2)(2.23 V - 2 V)2 = 2.65 mA
VDS = VDD - IDRD = 15 V - (2.65 mA)(3.3 kỈ) = 6.26 V
Rd = RD 7 RL = 3.3 kỈ 7 33 kỈ = 3 kỈ
2

The ac output voltage is
Vout = AvVin = gmRdVin = (23 mS)(3 kỈ)(25 mV) = 1.73 V
Related Problem

For the E-MOSFET in Figure 9–17, ID(on) = 25 mA at VGS = 5 V, VGS(th) = 1.5 V,
and gm = 10 mS. Find VGS, ID, VDS, and the ac output voltage. Vin = 25 mV.
Open the Multisim file E09-08 in the Examples folder on the companion website.
Determine ID, VDS, and Vout using the specified value of Vin. Compare with the
calculated values.


P REFACE

◆

VII

Application Activity This feature follows the last section in most chapters and is identified by a special graphic design. A practical application of devices or circuits covered in
the chapter is presented. The student learns how the specific device or circuit is used and is

taken through the steps of design specification, simulation, prototyping, circuit board
implementation, and testing. A typical Application Activity is shown in Figure P–4.
Application Activities are optional. Results are provided in the Online Instructor’s
Resource Manual.

368

◆

372

P OWER A MPLIFIERS

◆

Multisim®
Activity

P OWER A MPLIFIERS

Application Activity: The Complete PA System
The class AB power amplifier follows the audio preamp and drives the speaker as shown
in the PA system block diagram in Figure 7–34. In this application, the power amplifier is
developed and interfaced with the preamp that was developed in Chapter 6. The maximum
signal power to the speaker should be approximately 6 W for a frequency range of 70 Hz
to 5 kHz. The dynamic range for the input voltage is up to 40 mV. Finally, the complete PA
system is put together.

Simulate the audio amplifier using your Multisim software. Observe the operation
with the virtual oscilloscope.

Prototyping and Testing
Now that the circuit has been simulated, the prototype circuit is constructed and tested.
After the circuit is successfully tested on a protoboard, it is ready to be finalized on a
printed circuit board.
Lab Experiment
To build and test a similar circuit, go to Experiment 7 in your lab manual (Laboratory
Exercises for Electronic Devices by David Buchla and Steven Wetterling).

Microphone

Circuit Board

DC power supply

The power amplifier is implemented on a printed circuit board as shown in Figure 7–39.
Heat sinks are used to provide additional heat dissipation from the power transistors.
9. Check the printed circuit board and verify that it agrees with the schematic in
Figure 7–35. The volume control potentiometer is mounted off the PC board for
easy access.
10. Label each input and output pin according to function. Locate the single backside trace.

Speaker

Audio preamp

Power amplifier

(a) PA system block diagram
ᮡ

(b) Physical configuration

F I G U RE 7 – 3 4
Heat sink

The Power Amplifier Circuit
The schematic of the push-pull power amplifier is shown in Figure 7–35. The circuit is a
class AB amplifier implemented with Darlington configurations and diode current mirror
bias. Both a traditional Darlington pair and a complementary Darlington (Sziklai) pair are
used to provide sufficient current to an 8 Ỉ speaker load. The signal from the preamp is
ᮣ

FIGURE 7–35

Link to
experiment
in lab
manual

Printed
circuit
board

+15 V

Class AB power push-pull amplifier.
R2
1 k⍀

Q1

2N3904

Q2

D1

BD135

D2
Output

Q3

ᮡ

D3 2N3906

R1
150 k⍀

FI G UR E 7– 39

Power amplifier circuit board.

Input

Q5

Q4

2N3904

BD135

R3
220 ⍀

Troubleshooting the Power Amplifier Board
A power amplifier circuit board has failed the production test. Test results are shown in
Figure 7–40.
11. Based on the scope displays, list possible faults for the circuit board.
Putting the System Together

–15 V

ᮡ

The preamp circuit board and the power amplifier circuit board are interconnected and
the dc power supply (battery pack), microphone, speaker, and volume control potentiometer are attached, as shown in Figure 7–41.
12. Verify that the system interconnections are correct.

F IGURE P–4

Portion of a typical Application Activity section.

GreenTech Application Inserts These inserts are placed after each of the first six chapters to introduce renewable energy concepts and the application of electronic devices to
solar and wind technologies. Figure P–5 illustrates typical GreenTech Application pages.
Chapter End Matter
chapters:

The following pedagogical features are found at the end of most

◆

Summary

◆

Key Term Glossary

◆

Key Formulas

◆

True/False Quiz

◆

Circuit-Action Quiz

◆

Self-Test

◆

Basic Problems

◆

Advanced Problems

◆

Datasheet Problems (selected chapters)

◆

Application Activity Problems (many chapters)

◆

Multisim® Troubleshooting Problems (most chapters)

Simulations
are provided
for most
Application
Activity
circuits.


www.elsolucionario.org
VIII

◆

P REFACE

224

◆

G REEN T ECH A PPLIC ATION 4

B IPOL AR J UNCTION T RANSISTORS

GreenTech Application 4: Solar Power

◆

225

daily east-to-west movement. This is particularly important with concentrating collectors
that need to be oriented correctly to focus the sun on the active region.
Figure GA4–2 is an example showing the improvement in energy collection of a typical
tracking panel versus a nontracking panel for a flat solar collector. As you can see, tracking extends the time that a given output can be maintained.

In this GreenTech Application, solar tracking is examined. Solar tracking is the process of
moving the solar panel to track the daily movement of the sun and the seasonal changes
in elevation of the sun in the southern sky. The purpose of a solar tracker is to increase the
amount of solar energy that can be collected by the system. For flat-panel collectors, an
increase of 30% to 50% in collected energy can be realized with sun tracking compared
to fixed solar panels.

ᮣ

F IG U R E G A 4 – 2

Relative output voltage

Graphs of voltages in tracking and
nontracking (fixed) solar panels.

Tracking
Panel’s rated current

Before looking at methods for tracking, let’s review how the sun moves across the sky.
The daily motion of the sun follows the arc of a circle from east to west that has its axis
pointed north near the location of the North Star. As the seasons change from the winter
solstice to the summer solstice, the sun rises a little further to the north each day. Between
the summer solstice and the winter solstice, the sun moves further south each day. The
amount of the north-south motion depends on your location.

Nontracking

Time of day
6

7

8

9 10 11 12 1

2

3

4

5

6

7

Single-Axis Solar Tracking
There are several methods of implementing solar tracking. Two main ones are sensor controlled and timer controlled.

For flat-panel solar collectors, the most economical and generally most practical solution
to tracking is to follow the daily east-west motion, and not the annual north-south motion.
The daily east-to-west motion can be followed with a single-axis tracking system. There
are two basic single-axis systems: polar and azimuth. In a polar system, the main axis is
pointed to the polar north (North Star), as shown in Figure GA4–1(a). (In telescope
terminology, this is called an equatorial mounting.) The advantage is that the solar panel is
kept at an angle facing the sun at all times because it tracks the sun from east to west and
is angled toward the southern sky. In an azimuth tracking system, the motor drives the
solar panel and frequently multiple panels. The panels can be oriented horizontally but
still track the east-to-west motion of the sun. Although this does not intercept as much of
the sunlight during the seasons, it has less wind loading and is more feasible for long
rows of solar panels. Figure GA4–1(b) shows a solar array that is oriented horizontally
with the axis pointing to true north and uses azimuth tracking (east to west). As you can
see, sunlight will strike the polar-aligned panel more directly during the seasonal movement
of the sun than it will with the horizontal orientation of the azimuth tracker.

Polar North
(North Star)

West

Electric
motor
turns the
panels

Sensor-Controlled Solar Tracking
This type of tracking control uses photosensitive devices such as photodiodes or photoresistors. Typically, there are two light sensors for the azimuth control and two for the elevation control. Each pair senses the direction of light from the sun and activates the motor
control to move the solar panel to align perpendicular to the sun’s rays.
Figure GA4–3 shows the basic idea of a sensor-controlled tracker. Two photodiodes with
a light-blocking partition between them are mounted on the same plane as the solar panel.

SUN

SUN

Photodiodes

True North

Solar panel

East
Lower output

Higher output

West

Position control
circuits

East
(a) A single-axis polar-aligned tracker
ᮡ

(b) Single-axis azimuth tracker

F IGU RE G A4 – 1

Output rotates motor

Types of single-axis solar tracking.

(a) Outputs of the photodiodes are unequal if solar panel is not
directly facing the sun.

Some solar tracking systems combine both the azimuth and the elevation tracking, which
is known as dual-axis tracking. Ideally, the solar panel should always face directly
toward the sun so that the sun light rays are perpendicular to the panel. With dual-axis
tracking, the annual north-south motion of the sun can be followed in addition to the

ᮡ

ᮡ

(b) Outputs of the photodiodes are equal when solar
panel orientation is optimum.

F IG U R E G A 4 – 3

Simplified illustration of a light-sensing control for a solar-tracking system. Relative sizes are exaggerated to demonstrate the concept.

FIG UR E P – 5

Portion of a typical GreenTech Application.

Suggestions for Using This Textbook
As mentioned, this book covers discrete devices and circuits in Chapters 1 through 11 and
linear integrated circuits in Chapters 12 through 17. Chapter 18 introduces programming
concepts for device testing and is linked to Troubleshooting sections.
Option 1 (two terms) Chapters 1 through 11 can be covered in the first term.
Depending on individual preferences and program emphasis, selective coverage may be
necessary. Chapters 12 through 17 can be covered in the second term. Again, selective coverage may be necessary.
Option 2 (one term) By omitting certain topics and by maintaining a rigorous schedule,
this book can be used in one-term courses. For example, a course covering only discrete
devices and circuits would use Chapters 1 through 11 with, perhaps, some selectivity.
Similarly, a course requiring only linear integrated circuit coverage would use Chapters
12 through 17. Another approach is a very selective coverage of discrete devices and circuits
topics followed by a limited coverage of integrated circuits (only op-amps, for example).
Also, elements such as the Multisim exercises, Application Activities, and GreenTech
Applications can be omitted or selectively used.

To the Student
When studying a particular chapter, study one section until you understand it and only then
move on to the next one. Read each section and study the related illustrations carefully; think
about the material; work through each example step-by-step, work its Related Problem and
check the answer; then answer each question in the Section Checkup, and check your
answers. Don’t expect each concept to be completely clear after a single reading; you may

have to read the material two or even three times. Once you think that you understand the material, review the chapter summary, key formula list, and key term definitions at the end of the


P REFACE

chapter. Take the true/false quiz, the circuit-action quiz, and the self-test. Finally, work the assigned problems at the end of the chapter. Working through these problems is perhaps the
most important way to check and reinforce your comprehension of the chapter. By working
problems, you acquire an additional level of insight and understanding, and develop logical
thinking that reading or classroom lectures alone do not provide.
Generally, you cannot fully understand a concept or procedure by simply watching or
listening to someone else. Only hard work and critical thinking will produce the results
you expect and deserve.

Acknowledgments
Many capable people have contributed to the ninth edition of Electronic Devices. It has
been thoroughly reviewed and checked for both content and accuracy. Those at Prentice
Hall who have contributed greatly to this project throughout the many phases of development and production include Rex Davidson, Yvette Schlarman, and Wyatt Morris. Lois
Porter has once more done an outstanding job editing the manuscript. Thanks to Sudip
Sinha at Aptara for his management of the art and text programs. Dave Buchla contributed
extensively to the content of the book, helping to make this edition the best one yet. Gary
Snyder created the circuit files for the Multisim® features in this edition. Gary also wrote
Chapter 18, Basic Programming Concepts for Automated Testing. I wish to express my
appreciation to those already mentioned as well as the reviewers who provided many valuable suggestions and constructive criticism that greatly influenced this edition. These
reviewers are William Dolan, Kennebec Valley Community College; John Duncan, Kent
State University; Art Eggers, Community College of Southern Nevada; Paul Garrett, ITT
Technical Institute; Mark Hughes, Cleveland Community College; Lisa Jones, Southwest
Tennessee Community College; Max Rabiee, University of Cincinnati; and Jim Rhodes,
Blue Ridge Community College.
Tom Floyd

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B RIEF C ONTENTS

1

11

Thyristors

564

Diodes and Applications

30

12

The Operational Amplifier

602

3

Special-Purpose Diodes

112

13

Basic Op-Amp Circuits

667

4

Bipolar Junction Transistors

173

14

Special-Purpose Op-Amp Circuits

718

5

Transistor Bias Circuits

228

15

Active Filters

763

6

BJT Amplifiers

271

16

Oscillators

806

7

Power Amplifiers

339

17

Voltage Regulators

851

8

Field-Effect Transistors (FETs)

384

18

Basic Programming Concepts
for Automated Testing

890

9

FET Amplifiers and Switching Circuits

451

Amplifier Frequency Response

505

1

Introduction to Electronics

2

10

Answers to Odd-Numbered Problems
Glossary
Index

944

951

931


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C ONTENTS

1
1–1
1–2
1–3
1–4
1–5

2
2–1
2–2
2–3
2–4
2–5

2–6
2–7
2–8
2–9
2–10

3
3–1
3–2
3–3
3–4
3–5
3–6

4
4–1
4–2
4–3
4–4
4–5
4–6

Introduction to Electronics

1

The Atom 2
Materials Used in Electronics 7
Current in Semiconductors 11
N-Type and P-Type Semiconductors 14

The PN Junction 16
GreenTech Application 1: Solar Power 24

5

Diodes and Applications

30

Diode Operation 31
Voltage-Current (V-I) Characteristics 36
Diode Models 39
Half-Wave Rectifiers 44
Full-Wave Rectifiers 50
Power Supply Filters and Regulators 57
Diode Limiters and Clampers 64
Voltage Multipliers 71
The Diode Datasheet 73
Troubleshooting 76
Application Activity 85
GreenTech Application 2: Solar Power 108
Special-Purpose Diodes
The Zener Diode 113
Zener Diode Applications 120
The Varactor Diode 128
Optical Diodes 133
Other Types of Diodes 147
Troubleshooting 153
Application Activity 155
GreenTech Application 3: Solar Power

4–7
4–8

5–1
5–2
5–3
5–4

6
6–1
6–2
6–3
6–4
6–5
6–6
6–7
6–8
112

7
7–1
7–2
7–3
7–4

170

Bipolar Junction Transistors
Bipolar Junction Transistor (BJT) Structure

Basic BJT Operation 175
BJT Characteristics and Parameters 177
The BJT as an Amplifier 190
The BJT as a Switch 192
The Phototransistor 196

Transistor Categories and Packaging 199
Troubleshooting 201
Application Activity 208
GreenTech Application 4: Solar Power 224
Transistor Bias Circuits
The DC Operating Point 229
Voltage-Divider Bias 235
Other Bias Methods 241
Troubleshooting 248
Application Activity 252
GreenTech Application 5: Wind Power

228

267

BJT Amplifiers

271

Amplifier Operation 272
Transistor AC Models 275
The Common-Emitter Amplifier 278
The Common-Collector Amplifier 291

The Common-Base Amplifier 298
Multistage Amplifiers 301
The Differential Amplifier 304
Troubleshooting 310
Application Activity 314
GreenTech Application 6: Wind Power 335
Power Amplifiers

339

The Class A Power Amplifier 340
The Class B and Class AB Push-Pull
Amplifiers 346
The Class C Amplifier 357
Troubleshooting 365
Application Activity 368

173
174

8
8–1
8–2
8–3
8–4
8–5

Field-Effect Transistors (FETs)
The JFET 385
JFET Characteristics and Parameters

JFET Biasing 397
The Ohmic Region 408
The MOSFET 412

384
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XIV

◆

C ONTENTS

8–6
8–7
8–8
8–9

MOSFET Characteristics and Parameters
MOSFET Biasing 420
The IGBT 423
Troubleshooting 425
Application Activity 427

9

FET Amplifiers and Switching Circuits

9–1
9–2
9–3
9–4
9–5
9–6
9–7

10
10–1
10–2
10–3
10–4
10–5
10–6
10–7

11
11–1
11–2
11–3
11–4
11–5
11–6
11–7

12
12–1
12–2
12–3

12–4
12–5
12–6
12–7
12–8
12–9

417

13
13–1
13–2
13–3
13–4
451

The Common-Source Amplifier 452
The Common-Drain Amplifier 464
The Common-Gate Amplifier 467
The Class D Amplifier 470
MOSFET Analog Switching 474
MOSFET Digital Switching 479
Troubleshooting 482
Application Activity 485
Amplifier Frequency Response
Basic Concepts 506
The Decibel 509
Low-Frequency Amplifier Response 512
High-Frequency Amplifier Response 530
Total Amplifier Frequency Response 540

Frequency Response of Multistage Amplifiers
Frequency Response Measurements 546
Application Activity 549
Thyristors

14
14–1
14–2
14–3
14–4
14–5
505

15
543

564

The Four-Layer Diode 565
The Silicon-Controlled Rectifier (SCR) 568
SCR Applications 573
The Diac and Triac 578
The Silicon-Controlled Switch (SCS) 582
The Unijunction Transistor (UJT) 583
The Programmable Unijunction
Transistor (PUT) 588
Application Activity 590
The Operational Amplifier

15–1

15–2
15–3
15–4
15–5
15–6
15–7

16

602

Introduction to Operational Amplifiers 603
Op-Amp Input Modes and Parameters 605
Negative Feedback 613
Op-Amps with Negative Feedback 614
Effects of Negative Feedback on Op-Amp
Impedances 619
Bias Current and Offset Voltage 624
Open-Loop Frequency and Phase Responses 627
Closed-Loop Frequency Response 633
Troubleshooting 636
Application Activity 638
Programmable Analog Technology 644

Basic Op-Amp Circuits

667

Comparators 668
Summing Amplifiers 679

Integrators and Differentiators 687
Troubleshooting 694
Application Activity 698
Programmable Analog Technology 704

Special-Purpose Op-Amp Circuits

718

Instrumentation Amplifiers 719
Isolation Amplifiers 725
Operational Transconductance
Amplifiers (OTAs) 730
Log and Antilog Amplifiers 736
Converters and Other Op-Amp Circuits 742
Application Activity 744
Programmable Analog Technology 750

Active Filters

763

Basic Filter Responses 764
Filter Response Characteristics 768
Active Low-Pass Filters 772
Active High-Pass Filters 776
Active Band-Pass Filters 779
Active Band-Stop Filters 785
Filter Response Measurements 787
Application Activity 789

Programmable Analog Technology 794

Oscillators

806

16–1 The Oscillator 807
16–2 Feedback Oscillators 808
16–3 Oscillators with RC Feedback Circuits 810
16–4 Oscillators with LC Feedback Circuits 817
16–5 Relaxation Oscillators 825
16–6 The 555 Timer as an Oscillator 830
Application Activity 836
Programmable Analog Technology 840

17
17–1
17–2
17–3
17–4
17–5
17–6

Voltage Regulators
Voltage Regulation 852
Basic Linear Series Regulators 855
Basic Linear Shunt Regulators 860
Basic Switching Regulators 863
Integrated Circuit Voltage Regulators
Integrated Circuit Voltage Regulator

Configurations 875
Application Activity 879

851

869


C ON T ENTS

18
18–1
18–2
18–3
18–4
18–5
18–6

Basic Programming Concepts
for Automated Testing
Programming Basics 891
Automated Testing Basics 893
The Simple Sequential Program 898
Conditional Execution 900
Program Loops 905
Branching and Subroutines 913

Answers to Odd-Numbered Problems
890

Glossary
Index

944

951

931

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I NTRODUCTION
E LECTRONICS

TO

VISIT THE COMPANION WEBSITE

CHAPTER OUTLINE

1–1
1–2

1–3
1–4
1–5

The Atom
Materials Used in Electronics
Current in Semiconductors
N-Type and P-Type Semiconductors
The PN Junction
GreenTech Application 1: Solar Power

CHAPTER OBJECTIVES
◆
◆
◆
◆
◆

Describe the structure of an atom
Discuss insulators, conductors, and semiconductors and
how they differ
Describe how current is produced in a semiconductor
Describe the properties of n-type and p-type
semiconductors
Describe how a pn junction is formed

KEY TERMS
◆
◆
◆

◆
◆
◆
◆
◆
◆

Atom
Proton
Electron
Shell
Valence
Ionization
Free electron
Orbital
Insulator

1

◆
◆
◆
◆
◆
◆
◆
◆

Conductor
Semiconductor

Silicon
Crystal
Hole
Doping
PN junction
Barrier potential

Study aids for this chapter are available at
/>INTRODUCTION

Electronic devices such as diodes, transistors, and integrated
circuits are made of a semiconductive material. To understand how these devices work, you should have a basic
knowledge of the structure of atoms and the interaction of
atomic particles. An important concept introduced in this
chapter is that of the pn junction that is formed when two
different types of semiconductive material are joined. The pn
junction is fundamental to the operation of devices such as
the solar cell, the diode, and certain types of transistors.


2

◆

1–1

I NTRODUCTION

TO

E LECTRONICS

T HE A TOM
All matter is composed of atoms; all atoms consist of electrons, protons, and neutrons
except normal hydrogen, which does not have a neutron. Each element in the periodic
table has a unique atomic structure, and all atoms within a given element have the same
number of protons. At first, the atom was thought to be a tiny indivisible sphere. Later it
was shown that the atom was not a single particle but was made up of a small dense
nucleus around which electrons orbit at great distances from the nucleus, similar to the
way planets orbit the sun. Niels Bohr proposed that the electrons in an atom circle the
nucleus in different obits, similar to the way planets orbit the sun in our solar system. The
Bohr model is often referred to as the planetary model. Another view of the atom called
the quantum model is considered a more accurate representation, but it is difficult to
visualize. For most practical purposes in electronics, the Bohr model suffices and is
commonly used because it is easy to visualize.
After completing this section, you should be able to
❏

❏
❏

❏
❏

❏

Describe the structure of an atom
◆ Discuss the Bohr model of an atom
◆ Define electron, proton, neutron, and
nucleus

Define atomic number
Discuss electron shells and orbits
◆ Explain energy levels
Define valence electron
Discuss ionization
◆ Define free electron and ion
Discuss the basic concept of the quantum model of the atom

The Bohr Model

HISTORY NOTE
Niels Henrik David Bohr (October 7,
1885–November 18, 1962) was a
Danish physicist, who made
important contributions to
understanding the structure of the
atom and quantum mechanics by
postulating the “planetary” model
of the atom. He received the Nobel
prize in physics in 1922. Bohr drew
upon the work or collaborated
with scientists such as Dalton,
Thomson, and Rutherford, among
others and has been described as
one of the most influential
physicists of the 20th century.

An atom* is the smallest particle of an element that retains the characteristics of that element. Each of the known 118 elements has atoms that are different from the atoms of all
other elements. This gives each element a unique atomic structure. According to the classical Bohr model, atoms have a planetary type of structure that consists of a central nucleus
surrounded by orbiting electrons, as illustrated in Figure 1–1. The nucleus consists of positively charged particles called protons and uncharged particles called neutrons. The

basic particles of negative charge are called electrons.
Each type of atom has a certain number of electrons and protons that distinguishes it
from the atoms of all other elements. For example, the simplest atom is that of hydrogen,
which has one proton and one electron, as shown in Figure 1–2(a). As another example, the
helium atom, shown in Figure 1–2(b), has two protons and two neutrons in the nucleus and
two electrons orbiting the nucleus.

Atomic Number
All elements are arranged in the periodic table of the elements in order according to their
atomic number. The atomic number equals the number of protons in the nucleus, which is
the same as the number of electrons in an electrically balanced (neutral) atom. For example,
hydrogen has an atomic number of 1 and helium has an atomic number of 2. In their normal
(or neutral) state, all atoms of a given element have the same number of electrons as protons;
the positive charges cancel the negative charges, and the atom has a net charge of zero.
*All bold terms are in the end-of-book glossary. The bold terms in color are key terms and are also defined
at the end of the chapter.


T HE A TOM

Electron
ᮡ

Proton

Neutron

F IGURE 1–1

The Bohr model of an atom showing electrons in orbits around the nucleus, which consists of

protons and neutrons. The “tails” on the electrons indicate motion.

Nucleus

Nucleus

Electron
Electron
Electron

(a) Hydrogen atom
ᮡ

(b) Helium atom

F IGURE 1–2

Two simple atoms, hydrogen and helium.

Atomic numbers of all the elements are shown on the periodic table of the elements in
Figure 1–3.

Electrons and Shells
Energy Levels Electrons orbit the nucleus of an atom at certain distances from the nucleus. Electrons near the nucleus have less energy than those in more distant orbits. Only
discrete (separate and distinct) values of electron energies exist within atomic structures.
Therefore, electrons must orbit only at discrete distances from the nucleus.
Each discrete distance (orbit) from the nucleus corresponds to a certain energy level. In
an atom, the orbits are grouped into energy levels known as shells. A given atom has a
fixed number of shells. Each shell has a fixed maximum number of electrons. The shells
(energy levels) are designated 1, 2, 3, and so on, with 1 being closest to the nucleus. The

Bohr model of the silicon atom is shown in Figure 1–4. Notice that there are 14 electrons
and 14 each of protons and neutrons in the nucleus.

◆

3


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I NTRODUCTION

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E LECTRONICS

Helium
Atomic number = 2
1

2

H

He

3

4

Li

Be

Silicon
Atomic number = 14

5

6

7

8

9

10

B

C

N

O

F

Ne

11

12

13

14

15

16

17

18

Na

Mg

Al

Si

P

S

Cl

Ar

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

K

Ca

Sc

Ti

V

Cr

Mn

Fe

Co

Ni

Cu

Zn

Ga

Ge

As

Se

Br

Kr

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

Rb

Sr

Y

Zr

Nb

Mo

Tc

Ru

Rh

Pd

Ag

Cd

In

Sn

Sb

Te

I

Xe

55

56

*

Cs

Ba

87

88

Fr

Ra

**

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

Hf

Ta

W

Re

Os

Ir

Pt

Au

Hg

Tl

Pb

Bi

Po

At

Rn

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

Rf

Db

Sg

Bh

Hs

Mt

Ds

Rg

Cp

Uut

Uuq

Uup

Uuh

Uus

Uuo

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

La

Ce

Pr

Nd

Pm

Sm

Eu

Gd

Tb

Dy

Ho

Er

Tm

Yb

Lu

89

90

91

92

93

94

95

96

97

98

99

100

101

102

103

Ac

Th

Pa

U

Np

Pu

Am

Cm

Bk

Cf

Es

Fm

Md

No

Lr

ᮡ

FIG UR E 1 – 3

The periodic table of the elements. Some tables also show atomic mass.
ᮣ

FIG UR E 1 – 4

Illustration of the Bohr model of the

silicon atom.
Shell 3 Shell 2 Shell 1

Nucleus
14p, 14n

The Maximum Number of Electrons in Each Shell The maximum number of electrons (Ne) that can exist in each shell of an atom is a fact of nature and can be calculated by
the formula,
Equation 1–1

Ne ‫ ؍‬2n2
where n is the number of the shell. The maximum number of electrons that can exist in the
innermost shell (shell 1) is
Ne = 2n2 = 2(1)2 = 2


T HE A TOM

The maximum number of electrons that can exist in shell 2 is
Ne = 2n2 = 2(2)2 = 2(4) = 8
The maximum number of electrons that can exist in shell 3 is
Ne = 2n2 = 2(3)2 = 2(9) = 18
The maximum number of electrons that can exist in shell 4 is
Ne = 2n2 = 2(4)2 = 2(16) = 32

Valence Electrons
Electrons that are in orbits farther from the nucleus have higher energy and are less tightly
bound to the atom than those closer to the nucleus. This is because the force of attraction
between the positively charged nucleus and the negatively charged electron decreases with
increasing distance from the nucleus. Electrons with the highest energy exist in the outermost shell of an atom and are relatively loosely bound to the atom. This outermost shell is

known as the valence shell and electrons in this shell are called valence electrons. These
valence electrons contribute to chemical reactions and bonding within the structure of a
material and determine its electrical properties. When a valence electron gains sufficient
energy from an external source, it can break free from its atom. This is the basis for conduction in materials.

Ionization
When an atom absorbs energy from a heat source or from light, for example, the energies
of the electrons are raised. The valence electrons possess more energy and are more
loosely bound to the atom than inner electrons, so they can easily jump to higher energy
shells when external energy is absorbed by the atom.
If a valence electron acquires a sufficient amount of energy, called ionization energy, it
can actually escape from the outer shell and the atom’s influence. The departure of a valence
electron leaves a previously neutral atom with an excess of positive charge (more protons
than electrons). The process of losing a valence electron is known as ionization, and the
resulting positively charged atom is called a positive ion. For example, the chemical symbol
for hydrogen is H. When a neutral hydrogen atom loses its valence electron and becomes a
positive ion, it is designated Hϩ. The escaped valence electron is called a free electron.
The reverse process can occur in certain atoms when a free electron collides with the atom
and is captured, releasing energy. The atom that has acquired the extra electron is called a
negative ion. The ionization process is not restricted to single atoms. In many chemical reactions, a group of atoms that are bonded together can lose or acquire one or more electrons.
For some nonmetallic materials such as chlorine, a free electron can be captured by the
neutral atom, forming a negative ion. In the case of chlorine, the ion is more stable than the
neutral atom because it has a filled outer shell. The chlorine ion is designated as Cl-.

The Quantum Model
Although the Bohr model of an atom is widely used because of its simplicity and ease of
visualization, it is not a complete model. The quantum model, a more recent model, is considered to be more accurate. The quantum model is a statistical model and very difficult to
understand or visualize. Like the Bohr model, the quantum model has a nucleus of protons
and neutrons surrounded by electrons. Unlike the Bohr model, the electrons in the quantum model do not exist in precise circular orbits as particles. Two important theories underlie the quantum model: the wave-particle duality and the uncertainty principle.
◆

Wave-particle duality. Just as light can be both a wave and a particle (photon),
electrons are thought to exhibit a dual characteristic. The velocity of an orbiting electron is considered to be its wavelength, which interferes with neighboring electron
waves by amplifying or canceling each other.

◆

FYI
Atoms are extremely small and
cannot be seen even with the
strongest optical microscopes;
however, a scanning tunneling
microscope can detect a single
atom. The nucleus is so small and
the electrons orbit at such
distances that the atom is mostly
empty space. To put it in
perspective, if the proton in a
hydrogen atom were the size of a
golf ball, the electron orbit would
be approximately one mile away.
Protons and neutrons are
approximately the same mass. The
mass of an electron is 1> 1836 of a
proton. Within protons and
neutrons there are even smaller
particles called quarks.

5

6

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TO

E LECTRONICS

Uncertainly principle. As you know, a wave is characterized by peaks and valleys;
therefore, electrons acting as waves cannot be precisely identified in terms of their position. According to Heisenberg, it is impossible to determine simultaneously both the
position and velocity of an electron with any degree of accuracy or certainty. The result
of this principle produces a concept of the atom with probability clouds, which are
mathematical descriptions of where electrons in an atom are most likely to be located.

◆

FYI
De Broglie showed that every
particle has wave characteristics.
Schrodiger developed a wave
equation for electrons.

In the quantum model, each shell or energy level consists of up to four subshells called
orbitals, which are designated s, p, d, and f. Orbital s can hold a maximum of two electrons,
orbital p can hold six electrons, orbital d can hold ten electrons, and orbital f can hold fourteen electrons. Each atom can be described by an electron configuration table that shows
the shells or energy levels, the orbitals, and the number of electrons in each orbital. For
example, the electron configuration table for the nitrogen atom is given in Table 1–1. The

first full-size number is the shell or energy level, the letter is the orbital, and the exponent
is the number of electrons in the orbital.
ᮣ

TABLE 1–1

NOTATION

Electron configuration table for
nitrogen.

2

2 electrons in shell 1, orbital s

1s

2s2

EXPL ANATION

2p3

5 electrons in shell 2: 2 in orbital s, 3 in orbital p

Atomic orbitals do not resemble a discrete circular path for the electron as depicted in
Bohr’s planetary model. In the quantum picture, each shell in the Bohr model is a threedimensional space surrounding the atom that represents the mean (average) energy of the
electron cloud. The term electron cloud (probability cloud) is used to describe the area
around an atom’s nucleus where an electron will probably be found.

EXAMPLE 1–1

Using the atomic number from the periodic table in Figure 1–3, describe a silicon (Si)
atom using an electron configuration table.
Solution

ᮣ

The atomic number of silicon is 14. This means that there are 14 protons in the nucleus.
Since there is always the same number of electrons as protons in a neutral atom, there
are also 14 electrons. As you know, there can be up to two electrons in shell 1, eight in
shell 2, and eighteen in shell 3. Therefore, in silicon there are two electrons in shell 1,
eight electrons in shell 2, and four electrons in shell 3 for a total of 14 electrons. The
electron configuration table for silicon is shown in Table 1–2.

TABLE 1–2

NOTATION
2

2 electrons in shell 1, orbital s

1s

2

Related Problem*

EXPL ANATION

2s

2p

6

8 electrons in shell 2: 2 in orbital s, 6 in orbital p

3s2

3p2

4 electrons in shell 3: 2 in orbital s, 2 in orbital p

Develop an electron configuration table for the germanium (Ge) atom in the periodic table.
*

Answers can be found at www.pearsonhighered.com/floyd.

In a three-dimensional representation of the quantum model of an atom, the s-orbitals
are shaped like spheres with the nucleus in the center. For energy level 1, the sphere is
“solid” but for energy levels 2 or more, each single s-orbital is composed of spherical surfaces
that are nested shells. A p-orbital for shell 2 has the form of two ellipsoidal lobes with a
point of tangency at the nucleus (sometimes referred to as a dumbbell shape.) The three