• Home
  • Textbooks
  • Electronic Devices and Circuit Theory
  • Bipolar Junction Transistors

Electronic Devices and Circuit Theory

Robert Boylestad, Louis Nashelsky

Chapter 3

Bipolar Junction Transistors - all with Video Answers

Educators

Chapter Questions

00:39

Problem 1

What names are applied to the two types of BJT transistors? Sketch the basic construction of each and label the various minority and majority carriers in each. Draw the graphic symbol next to each. Is any of this information altered by changing from a silicon to a germanium base?

Manish Kumar
Manish Kumar
Numerade Educator
02:44

Problem 2

What is the major difference between a bipolar and a unipolar device?

Shazia Naz
Shazia Naz
Numerade Educator
01:21

Problem 3

How must the two transistor junctions be biased for proper transistor amplifier operation?

Ajay Singhal
Ajay Singhal
Numerade Educator
02:24

Problem 4

What is the source of the leakage current in a transistor?

kj
Karl Jacob
Numerade Educator
02:04

Problem 5

Sketch a figure similar to Fig. 4 a for the forward-biased junction of an $n p n$ transistor. Describe the resulting carrier motion.

Chai Santi
Chai Santi
Numerade Educator
01:54

Problem 6

Sketch a figure similar to Fig. $4 \mathrm{~b}$ for the reverse-biased junction of an $n p n$ transistor. Describe the resulting carrier motion.

Chai Santi
Chai Santi
Numerade Educator
02:04

Problem 7

Sketch a figure similar to Fig. 5 for the majority-and minority-carrier flow of an $n p n$ transistor. Describe the resulting carrier motion.

Chai Santi
Chai Santi
Numerade Educator
01:30

Problem 8

Which of the transistor currents is always the largest? Which is always the smallest? Which two currents are relatively close in magnitude?

Ajay Singhal
Ajay Singhal
Numerade Educator
01:10

Problem 9

If the emitter current of a transistor is $8 \mathrm{~mA}$ and $I_{B}$ is $1 / 100$ of $I_{C}$, determine the levels of $I_{C}$ and $I_{B}$.

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
01:38

Problem 10

From memory, sketch the transistor symbol for a $p n p$ and an $n p n$ transistor, and then insert the conventional flow direction for each current.

Ajay Singhal
Ajay Singhal
Numerade Educator
01:45

Problem 11

Using the characteristics of Fig. 7 , determine $V_{B E}$ at $I_{E}=5 \mathrm{~mA}$ for $V_{C B}=1,10$, and $20 \mathrm{~V}$. Is it reasonable to assume on an approximate basis that $V_{C B}$ has only a slight effect on the relationship between $V_{B E}$ and $I_{E}$ ?

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
05:22

Problem 12

a. Determine the average ac resistance for the characteristics of Fig. $10 \mathrm{~b}$.
b. For networks in which the magnitude of the resistive elements is typically in kilohms, is the approximation of Fig. $10 \mathrm{c}$ a valid one [based on the results of part (a)]?

Vishal Gupta
Vishal Gupta
Numerade Educator
01:42

Problem 13

a. Using the characteristics of Fig. 8 , determine the resulting collector current if $I_{E}=3.5 \mathrm{~mA}$ and $V_{C B}=10 \mathrm{~V}$.
b. Repeat part (a) for $I_{E}=3.5 \mathrm{~mA}$ and $V_{C B}=20 \mathrm{~V}$.
c. How have the changes in $V_{C B}$ affected the resulting level of $I_{C}$ ?
d. On an approximate basis, how are $I_{E}$ and $I_{C}$ related based on the results above?

Ben Nicholson
Ben Nicholson
Numerade Educator
01:55

Problem 14

a. Using the characteristics of Figs. 7 and 8 , determine $I_{C}$ if $V_{C B}=5 \mathrm{~V}$ and $V_{B E}=0.7 \mathrm{~V}$.
b. Determine $V_{B E}$ if $I_{C}=5 \mathrm{~mA}$ and $V_{C B}=15 \mathrm{~V}$.
c. Repeat part (b) using the characteristics of Fig. 10b.
d. Repeat part (b) using the characteristics of Fig. $10 \mathrm{c}$.
e. Compare the solutions for $\mathrm{V}_{B E}$ for parts (b) through (d). Can the difference be ignored if voltage levels greater than a few volts are typically encountered?

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
05:45

Problem 15

a. Given an $\alpha_{\mathrm{dc}}$ of $0.998$, determine $I_{C}$ if $I_{E}=4 \mathrm{~mA}$.
b. Determine $\alpha_{\mathrm{dc}}$ if $I_{E}=2.8 \mathrm{~mA}$ and $I_{B}=20 \mu \mathrm{A}$.
c. Find $I_{E}$ if $I_{B}=40 \mu \mathrm{A}$ and $\alpha_{\mathrm{dc}}$ is $0.98$.

Sunita Kumari
Sunita Kumari
Numerade Educator
00:39

Problem 16

From memory only, sketch the common-base BJT transistor configuration (for $n p n$ and $p n p$ ) and indicate the polarity of the applied bias and resulting current directions.

Chai Santi
Chai Santi
Numerade Educator
00:58

Problem 17

Define $I_{C B O}$ and $I_{C E O}$. How are they different? How are they related? Are they typically close in magnitude?

David Collins
David Collins
Numerade Educator
01:17

Problem 18

Using the characteristics of Fig. 13:
a. Find the value of $I_{C}$ corresponding to $V_{B E}=+750 \mathrm{mV}$ and $V_{C E}=+4 \mathrm{~V}$.
b. Find the value of $V_{C E}$ and $V_{B E}$ corresponding to $I_{C}=3.5 \mathrm{~mA}$ and $I_{B}=30 \mu \mathrm{A}$.

Saman Zulfiqar
Saman Zulfiqar
Numerade Educator
02:06

Problem 19

a. For the common-emitter characteristics of Fig. 13 , find the dc beta at an operating point of $V_{C E}=6 \mathrm{~V}$ and $I_{C}=3 \mathrm{~mA}$
b. Find the value of $\alpha$ corresponding to this operating point.
c. At $V_{C E}=+6 \mathrm{~V}$, find the corresponding value of $I_{C E O}$.
d. Calculate the approximate value of $I_{C B O}$ using the de beta value obtained in part (a).

Chai Santi
Chai Santi
Numerade Educator
01:17

Problem 20

a. Using the characteristics of Fig. 13a, determine $I_{C E O}$ at $V_{C E}=10 \mathrm{~V}$.
b. Determine $\beta_{\text {dc }}$ at $I_{B}=10 \mu \mathrm{A}$ and $V_{C E}=10 \mathrm{~V}$.
c. Using the $\beta_{\mathrm{dc}}$ determined in part (b), calculate $I_{C B O}$.

Saman Zulfiqar
Saman Zulfiqar
Numerade Educator
10:01

Problem 21

a. Using the characteristics of Fig. 13a, determine $\beta_{\mathrm{dc}}$ at $I_{B}=60 \mu \mathrm{A}$ and $V_{C E}=4 \mathrm{~V}$.
b. Repeat part (a) at $I_{B}=30 \mu \mathrm{A}$ and $V_{C E}=7 \mathrm{~V}$.
c. Repeat part (a) at $I_{B}=10 \mu \mathrm{A}$ and $V_{C E}=10 \mathrm{~V}$.
d. Reviewing the results of parts (a) through (c), does the value of $\beta_{\mathrm{dc}}$ change from point to point on the characteristics? Where were the higher values found? Can you develop any general conclusions about the value of $\beta_{\mathrm{dc}}$ on a set of characteristics such as those provided in Fig. $13 \mathrm{a}$ ?

AG
Ankit Gupta
Numerade Educator
01:17

Problem 22

a. Using the characteristics of Fig. 13a, determine $\beta_{\mathrm{ac}}$ at $I_{B}=60 \mu \mathrm{A}$ and $V_{C E}=4 \mathrm{~V}$.
b. Repeat part (a) at $I_{B}=30 \mu \mathrm{A}$ and $V_{C E}=7 \mathrm{~V}$.
c. Repeat part (a) at $I_{B}=10 \mu \mathrm{A}$ and $V_{C E}=10 \mathrm{~V}$.
d. Reviewing the results of parts (a) through (c), does the value of $\beta_{\mathrm{ac}}$ change from point to point on the characteristics? Where are the high values located? Can you develop any general conclusions about the value of $\beta_{\mathrm{ac}}$ on a set of collector characteristics?
e. The chosen points in this exercise are the same as those employed in Problem 21 . If Problem 21 was performed, compare the levels of $\beta_{\mathrm{dc}}$ and $\beta_{\mathrm{ac}}$ for each point and comment on the trend in magnitude for each quantity.

Saman Zulfiqar
Saman Zulfiqar
Numerade Educator
04:54

Problem 23

Using the characteristics of Fig. 13a, determine $\beta_{\text {dc }}$ at $I_{B}=25 \mu \mathrm{A}$ and $V_{C E}=10 \mathrm{~V}$. Then calculate $\alpha_{\mathrm{dc}}$ and the resulting level of $I_{E}$. (Use the level of $I_{C}$ determined by $I_{C}=\beta_{\mathrm{dc}} I_{B}$.)

Manish Kumar ( Iit K )
Manish Kumar ( Iit K )
Numerade Educator
07:20

Problem 24

a. Given that $\alpha_{\mathrm{dc}}=0.980$, determine the corresponding value of $\beta_{\mathrm{dc}}$
b. Given $\beta_{\mathrm{dc}}=120$, determine the corresponding value of $\alpha$.
c. Given that $\beta_{\mathrm{dc}}=120$ and $I_{C}=2.0 \mathrm{~mA}$, find $I_{E}$ and $I_{B}$.

Ralph Maestre
Ralph Maestre
Numerade Educator
01:13

Problem 25

From memory only, sketch the common-emitter configuration (for $n p n$ and $p n p$ ) and insert the proper biasing arrangement with the resulting current directions for $I_{B}, I_{C}$, and $I_{E}$.

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
01:54

Problem 26

An input voltage of $2 \mathrm{~V} \mathrm{rms}$ (measured from base to ground) is applied to the circuit of Fig. 21 . Assuming that the emitter voltage follows the base voltage exactly and that $V_{b e}(\mathrm{rms})=0.1 \mathrm{~V}$, calculate the circuit voltage amplification $\left(A_{v}=V_{o} / V_{i}\right)$ and emitter current for $R_{E}=1 \mathrm{k} \Omega$.

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
01:45

Problem 27

For a transistor having the characteristics of Fig. 13 , sketch the input and output characteristics of the common-collector configuration.

Ajay Singhal
Ajay Singhal
Numerade Educator
02:24

Problem 28

Determine the region of operation for a transistor having the characteristics of Fig. 13 if $I_{C_{\max }}=6 \mathrm{~mA}, B V_{C E O}=15 \mathrm{~V}$, and $P_{C_{\max }}=35 \mathrm{~mW}$.

Amit Srivastava
Amit Srivastava
Numerade Educator
02:24

Problem 29

Determine the region of operation for a transistor having the characteristics of Fig. 8 if $I_{C_{\max }}=7 \mathrm{~mA}, B V_{C B O}=20 \mathrm{~V}$, and $P_{C_{\max }}=42 \mathrm{~mW}$.

Amit Srivastava
Amit Srivastava
Numerade Educator
01:06

Problem 30

Referring to Fig. 23 , determine the temperature range for the device in degrees Fahrenheit.

David Collins
David Collins
Numerade Educator
01:35

Problem 31

Using the information provided in Fig. 23 regarding $P_{D_{\max }}, V_{C E_{\max }}, I_{C_{\max }}$ and $V_{C E_{\text {sat }}}$, sketch the boundaries of operation for the device.

Vishal Gupta
Vishal Gupta
Numerade Educator
01:09

Problem 32

Based on the data of Fig. 23, what is the expected value of $I_{C E O}$ using the average value of $\beta_{\mathrm{dc}}$ ?

Prabhakar Kumar
Prabhakar Kumar
Numerade Educator
07:29

Problem 33

How does the range of $h_{F E}$ (Fig. 23c, normalized from $h_{F E}=100$ ) compare with the range of $h_{f e}$ (Fig. 23b) for the range of $I_{C}$ from $0.1$ to $10 \mathrm{~mA}$ ?

Mirza Aslam Beig
Mirza Aslam Beig
Numerade Educator
00:25

Problem 34

Using the characteristics of Fig. $23 \mathrm{~d}$, determine whether the input capacitance in the common base configuration increases or decreases with increasing levels of reverse-bias potential. Can you explain why?

Dading Chen
Dading Chen
Numerade Educator
06:05

Problem 35

Using the characteristics of Fig. $23 \mathrm{~b}$, determine how much the level of $h_{f e}$ has changed from its value at $1 \mathrm{~mA}$ to its value at $10 \mathrm{~mA}$. Note that the vertical scale is a log scale that may require reference to Section 2 of the chapter "Op-Amp Applications". Is the change one that should be considered in a design situation?

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
03:45

Problem 36

Using the characteristics of Fig. $23 \mathrm{c}$, determine the level of $\beta_{\mathrm{dc}}$ at $I_{C}=10 \mathrm{~mA}$ at the three levels of temperature appearing in the figure. Is the change significant for the specified temperature range? Is it an element to be concerned about in the design process?

Amit Srivastava
Amit Srivastava
Numerade Educator
View

Problem 37

a. Using the characteristics of Fig. 24, determine $\beta_{\mathrm{ac}}$ at $I_{C}=14 \mathrm{~mA}$ and $V_{C E}=3 \mathrm{~V}$.
b. Determine $\beta_{\mathrm{dc}}$ at $I_{C}=1 \mathrm{~mA}$ and $V_{C E}=8 \mathrm{~V}$.
c. Determine $\beta_{\mathrm{ac}}$ at $I_{C}=14 \mathrm{~mA}$ and $V_{C E}=3 \mathrm{~V}$.
d. Determine $\beta_{\mathrm{dc}}$ at $I_{C}=1 \mathrm{~mA}$ and $V_{C E}=8 \mathrm{~V}$.
e. How does the level of $\beta_{\mathrm{ac}}$ and $\beta_{\mathrm{dc}}$ compare in each region?
f. Is the approximation $\beta_{\mathrm{dc}} \cong \beta_{\mathrm{ac}}$ a valid one for this set of characteristics?

Victor Salazar
Victor Salazar
Numerade Educator