Download Electronic Devices Conventional Current Version Thomas L. Floyd

Electronic Devices: Conventional Current Version
Floyd
9e
ISBN 978-1-29202-564-3
9 781292 025643
Electronic Devices
Conventional Current Version
Thomas L. Floyd
Ninth Edition
Pearson Education Limited
Edinburgh Gate
Harlow
Essex CM20 2JE
England and Associated Companies throughout the world
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book by such owners.
ISBN 10: 1-292-02564-6
ISBN 13: 978-1-292-02564-3
British Library Cataloguing-in-Publication Data
A catalogue record for this book is available from the British Library
Printed in the United States of America
T RANSISTOR B IAS C IRCUITS
Power (kW)
Maximum power output
200
180
160
140
120
100
80
60
40
20
0
Furling
Shut down
0
Cut in
䊱
5
10
15
20
25
30
35
40
45
Wind speed (mph)
Start up
F IGURE GA – 5
Example of a wind power curve for a wind turbine.
Questions
Some questions may require research beyond the content of this coverage.
1. What does HAWT stand for?
2. Why does the input voltage to the ac-to-dc converter vary in amplitude and
frequency?
3. What are the physical factors that determine the amount of power available in the
wind that strikes the blades of a turbine?
4. What is the Betz limit?
5. In wind farms, how close together should the turbines generally be placed?
The following websites are recommended for viewing HAWTs in action.
Many other websites are also available.
http://www.youtube.com/watch?v=eXejxcW-XGo
http://www.youtube.com/watch?v=RFPj9frhKuo
http://www.youtube.com/watch?v=7PLvr-lpADM&NR=1
http://www.youtube.com/watch?v=7rlVMJgPRc4
http://www.youtube.com/watch?v=NeVClBaQI_Q
http://www.youtube.com/watch?v=PEEAl9laoUg
http://www.youtube.com/watch?v=N9_FKGxD27g
http://www.youtube.com/watch?v=v05MuBseBQE
http://www.youtube.com/watch?v=hBRfboAscww
280
T RANSISTOR B IAS C IRCUITS
ANSWERS TO ODD-NUMBERED PROBLEMS
(c) Transistor shorted
collector-to-emitter
1. Saturation
3. 18 mA
37. (a) 1: 10 V,
(d) Open emitter
2: float,
3: -3.59 V,
4: 10 V
7. See Figure ANS–1.
(b) 1: 10 V,
2: 4.05 V,
3:
4.75 V,
4: 4.05 V
9. (a) IC(sat) = 50 mA
(c) 1: 10 V,
2: 0 V,
3:
0 V,
4: 10 V
(b) VCE(CUTOFF) = 10 V
(d) 1: 10 V,
2: 570 mV,
3:
1.27 V,
4: float
(c) IB = 250 mA; IC = 25 mA; VCE = 5 V
(e) 1: 10 V,
2: 0 V,
3:
0.7 V,
4: 0 V
(f) 1: 10 V,
2: 0 V,
3:
3.59 V,
4: 10 V
5. VCE = 20 V; IC(sat) = 2 mA
39. R1 open, R2 shorted, BE junction open
41. VC = VCC = 9.1 V, VB normal, VE = 0 V
PD(min) = 20 mW
186 k⍀
45. 457 mW
+
+
10 V
43. None are exceeded.
1.2 k⍀
–
10 V
47. See Figure ANS–3.
–
+15 V
䊱
F IGUR E A NS– 1
RC
2.0 k⍀
11. 63.2
RB
13. IC ⬵ 809 mA; VCE = 13.2 V
2N3904
Nearest standard values
assuming βDC = 100
286 k⍀
15. See Figure ANS–2.
VEE
+9 V
RE
1.0 k⍀
R2
15 k⍀
䊱
FIGURE ANS–3
49. See Figure ANS–4.
9V
R1
47 k⍀
RC
2.2 k⍀
R1
2.0 k⍀
RC
3.0 k⍀
2N3904
䊱
R2
620 ⍀
F IGUR E A NS– 2
17. (a) -1.63 mA, -8.16 V
RE
1.0 k⍀
(b) 13.3 mW
19. VB = -186 mV; VE = -0.886 V; VC = 3.14 V
䊱
21. 0.09 mA
FIGURE ANS–4
23. IC = 16.3 mA; VCE = -6.95 V
25. 2.53 kÆ
51. Yes
27. 7.87 mA; 2.56 V
29. ICQ = 92.5 mA; VCEQ = 2.75 V
53. VCEQ will be less, causing the transistor to saturate at a slightly
higher temperature, thus limiting the low temperature response.
31. 27.7 mA to 69.2 mA; 6.23 V to 2.08 V; Yes
55. RC open
33. V1 = 0 V, V2 = 0 V, V3 = 8 V
57. R2 open
35. (a) Open collector
(b) No problems
59. RC shorted
281
282
BJT A MPLIFIERS
APPLICATION ACTIVITY PREVIEW
CHAPTER OUTLINE
Amplifier Operation
Transistor AC Models
The Common-Emitter Amplifier
The Common-Collector Amplifier
The Common-Base Amplifier
Multistage Amplifiers
The Differential Amplifier
Troubleshooting
Application Activity
GreenTech Application: Wind Power
1
2
3
4
5
6
7
8
CHAPTER OBJECTIVES
◆
◆
◆
◆
◆
◆
◆
◆
Describe amplifier operation
Discuss transistor models
Describe and analyze the operation of common-emitter
amplifiers
Describe and analyze the operation of common-collector
amplifiers
Describe and analyze the operation of common-base
amplifiers
Describe and analyze the operation of multistage
amplifiers
Discuss the differential amplifier and its operation
Troubleshoot amplifier circuits
The Application Activity in this chapter involves a preamplifier
circuit for a public address system. The complete system
includes the preamplifier, a power amplifier, and a dc power
supply. You will focus on the preamplifier in this chapter.
VISIT THE COMPANION WEBSITE
Study aids and Multisim files for this chapter are available at
http://www.pearsonhighered.com/electronics
INTRODUCTION
The things you learned about biasing a transistor are now
applied in this chapter where bipolar junction transistor
(BJT) circuits are used as small-signal amplifiers. The term
small-signal refers to the use of signals that take up a relatively small percentage of an amplifier’s operational range.
Additionally, you will learn how to reduce an amplifier to an
equivalent dc and ac circuit for easier analysis, and you will
learn about multistage amplifiers. The differential amplifier
is also covered.
KEY TERMS
◆
◆
◆
◆
◆
◆
◆
◆
r parameter
Common-emitter
ac ground
Input resistance
Output resistance
Attenuation
Bypass capacitor
Common-collector
◆
◆
◆
◆
◆
◆
Emitter-follower
Common-base
Decibel
Differential amplifier
Common mode
CMRR (Common-mode
rejection ratio)
From Chapter 6 of Electronic Devices: Conventional Current Version, Ninth Edition, Thomas L. Floyd. Copyright © 2012 by Pearson
Education, Inc. Published by Pearson Prentice Hall. All rights reserved.
283
BJT A MPLIFIERS
1 A MPLIFIER O PE R ATI O N
The biasing of a transistor is purely a dc operation. The purpose of biasing is to establish a Q-point about which variations in current and voltage can occur in response to
an ac input signal. In applications where small signal voltages must be amplified—
such as from an antenna or a microphone—variations about the Q-point are relatively
small. Amplifiers designed to handle these small ac signals are often referred to as
small-signal amplifiers.
After completing this section, you should be able to
❏
❏
❏
HISTORY NOTE
The American inventor Lee De
Forest (1873–1961) is one of
several pioneers of radio
development. De Forest
experimented with receiving longdistance radio signals and in 1907
patented an electronic device
named the audion, which was the
first amplifier. De Forest’s new
three-electrode (triode) vacuum
tube boosted radio waves as they
were received and made possible
what was then called “wireless
telephony,” which allowed the
human voice, music, or any
broadcast signal to be heard.
Describe amplifier operation
Identify ac quantities
◆ Distinguish ac quantities from dc quantities
Discuss the operation of a linear amplifier
◆ Define phase inversion
◆ Graphically illustrate amplifier operation
◆ Analyze ac load line operation
AC Quantities
In the previous chapters, dc quantities were identified by nonitalic uppercase (capital) subscripts such as IC, IE, VC, and VCE. Lowercase italic subscripts are used to indicate ac quantities of rms, peak, and peak-to-peak currents and voltages: for example, Ic, Ie, Ib, Vc, and
Vce (rms values are assumed unless otherwise stated). Instantaneous quantities are represented by both lowercase letters and subscripts such as ic, ie, ib, and vce. Figure 1 illustrates
these quantities for a specific voltage waveform.
䊳
FIG UR E 1
Vce can represent rms, average, peak,
or peak-to-peak, but rms will be
assumed unless stated otherwise. vce
can be any instantaneous value on
the curve.
V
rms
avg
Vce
Vce Vce
VCE
Vce
vce
0
t
0
In addition to currents and voltages, resistances often have different values when a circuit is analyzed from an ac viewpoint as opposed to a dc viewpoint. Lowercase subscripts
are used to identify ac resistance values. For example, Rc is the ac collector resistance, and
RC is the dc collector resistance. You will see the need for this distinction later. Resistance
values internal to the transistor use a lowercase r¿ to show it is an ac resistance. An example is the internal ac emitter resistance, r¿e.
284