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Electronic Devices and Circuit Theory

Robert Boylestad, Louis Nashelsky

Chapter 1

Semiconductor Diodes - all with Video Answers

Educators

Chapter Questions

02:24

Problem 1

Sketch the atomic structure of copper and discuss why it is a good conductor and how its structure is different from that of germanium, silicon, and gallium arsenide.

Jerrah Biggerstaff
Jerrah Biggerstaff
Numerade Educator
01:11

Problem 2

In your own words, define an intrinsic material, a negative temperature coefficient, and covalent bonding.

Lottie Adams
Lottie Adams
Numerade Educator
00:55

Problem 3

Consult your reference library and list three materials that have a negative temperature coefficient and three that have a positive temperature coefficient.

Emily Himsel
Emily Himsel
Numerade Educator
01:33

Problem 4

a. How much energy in joules is required to move a charge of $12 \mu \mathrm{C}$ through a difference in potential of $6 \mathrm{~V}$ ?
b. For part (a), find the energy in electron-volts.

Nishant Kumar
Nishant Kumar
Numerade Educator
00:36

Problem 5

If $48 \mathrm{eV}$ of energy is required to move a charge through a potential difference of $3.2 \mathrm{~V}$, determine the charge involved.

Mayukh Banik
Mayukh Banik
Numerade Educator
02:07

Problem 6

Consult your reference library and determine the level of $E_{g}$ for GaP, ZnS, and GaAsP, three semiconductor materials of practical value. In addition, determine the written name for each material.

Chai Santi
Chai Santi
Numerade Educator
01:38

Problem 7

Describe the difference between $n$ -type and $p$ -type semiconductor materials.

Sanchit Jain
Sanchit Jain
Numerade Educator
01:24

Problem 8

Describe the difference between donor and acceptor impurities.

Dennis Howard
Dennis Howard
Numerade Educator
01:32

Problem 9

Describe the difference between majority and minority carriers.

Ajay Singhal
Ajay Singhal
Numerade Educator
02:08

Problem 10

Sketch the atomic structure of silicon and insert an impurity of arsenic as demonstrated for silicon in Fig. 7 .

Sima Sarker
Sima Sarker
Numerade Educator
03:50

Problem 11

Repeat Problem 10 , but insert an impurity of indium.

Linda Winkler
Linda Winkler
Numerade Educator
View

Problem 12

Consult your reference library and find another explanation of hole versus electron flow. Using both descriptions, describe in your own words the process of hole conduction.

Rashmi Sinha
Rashmi Sinha
Numerade Educator
00:00

Problem 13

Describe in your own words the conditions established by forward- and reverse-bias conditions on a $p-n$ junction diode and how the resulting current is affected.

Vinnu M
Vinnu M
Numerade Educator
00:00

Problem 14

Describe how you will remember the forward- and reverse-bias states of the $p-n$ junction diode. That is, how will you remember which potential (positive or negative) is applied to which terminal?

Vinnu M
Vinnu M
Numerade Educator
01:02

Problem 15

a. Determine the thermal voltage for a diode at a temperature of $20^{\circ} \mathrm{C}$.
b. For the same diode of part (a), find the diode current using Eq. 2 if $I_{s}=40 \mathrm{nA}, n=2$ (low value of $V_{D}$ ), and the applied bias voltage is $0.5 \mathrm{~V}$.

Kratika Bhadauria
Kratika Bhadauria
Numerade Educator
00:37

Problem 16

Repeat Problem 15 for $T=100^{\circ} \mathrm{C}$ (boiling point of water). Assume that $I_{s}$ has increased to $5.0 \mu \mathrm{A}$.

Victor Salazar
Victor Salazar
Numerade Educator
02:54

Problem 17

a. Using Eq. (2), determine the diode current at $20^{\circ} \mathrm{C}$ for a silicon diode with $n=2, I_{s}=$ $0.1 \mu \mathrm{A}$ at a reverse-bias potential of $-10 \mathrm{~V}$.
b. Is the result expected? Why?

Narayan Hari
Narayan Hari
Numerade Educator
01:02

Problem 18

Given a diode current of $8 \mathrm{~mA}$ and $n=1$, find $I_{s}$ if the applied voltage is $0.5 \mathrm{~V}$ and the temperature is room temperature $\left(25^{\circ} \mathrm{C}\right)$.

Kratika Bhadauria
Kratika Bhadauria
Numerade Educator
02:26

Problem 19

Given a diode current of $6 \mathrm{~mA}, V_{T}=26 \mathrm{mV}, n=1$, and $I_{s}=1 \mathrm{nA}$, find the applied voltage $V_{D}$.

Narayan Hari
Narayan Hari
Numerade Educator
00:34

Problem 20

a. Plot the function $y=e^{x}$ for $x$ from 0 to 10 . Why is it difficult to plot?
b. What is the value of $y=e^{x}$ at $x=0$ ?
c. Based on the results of part (b), why is the factor $-1$ important in Eq. (2)?

M S
M S
Numerade Educator
01:34

Problem 21

In the reverse-bias region the saturation current of a silicon diode is about $0.1 \mu \mathrm{A}\left(T=20^{\circ} \mathrm{C}\right)$. Determine its approximate value if the temperature is increased $40^{\circ} \mathrm{C}$.

Anand Jangid
Anand Jangid
Numerade Educator
01:45

Problem 22

Compare the characteristics of a silicon and a germanium diode and determine which you would prefer to use for most practical applications. Give some details. Refer to a manufacturer's listing and compare the characteristics of a germanium and a silicon diode of similar maximum ratings.

Grigoriy Sereda
Grigoriy Sereda
Numerade Educator
01:02

Problem 23

Determine the forward voltage drop across the diode whose characteristics appear in Fig. 19 at temperatures of $-75^{\circ} \mathrm{C}, 25^{\circ} \mathrm{C}, 125^{\circ} \mathrm{C}$ and a current of $10 \mathrm{~mA}$. For each temperature, determine the level of saturation current. Compare the extremes of each and comment on the ratio of the two.

Kratika Bhadauria
Kratika Bhadauria
Numerade Educator
00:55

Problem 24

Describe in your own words the meaning of the word ideal as applied to a device or a system.

Nicole Smina
Nicole Smina
Numerade Educator
00:39

Problem 25

Describe in your own words the characteristics of the ideal diode and how they determine the on and off states of the device. That is, describe why the short-circuit and open-circuit equivalents are appropriate.

Manish Kumar
Manish Kumar
Numerade Educator
00:44

Problem 26

What is the one important difference between the characteristics of a simple switch and those of an ideal diode?

Jorge Villanueva
Jorge Villanueva
Numerade Educator
04:44

Problem 27

Determine the static or dc resistance of the commercially available diode of Fig. 15 at a forward current of $4 \mathrm{~mA}$.

Pawan Yadav
Pawan Yadav
Numerade Educator
04:03

Problem 28

Repeat Problem 27 at a forward current of $15 \mathrm{~mA}$ and compare results.

Dading Chen
Dading Chen
Numerade Educator
03:01

Problem 29

Determine the static or dc resistance of the commercially available diode of Fig. 15 at a reverse voltage of $-10 \mathrm{~V}$. How does it compare to the value determined at a reverse voltage of $-30 \mathrm{~V} ?$

Hubert Agamasu
Hubert Agamasu
Numerade Educator
04:44

Problem 30

Calculate the dc and ac resistances for the diode of Fig. 15 at a forward current of $10 \mathrm{~mA}$ and compare their magnitudes.

Pawan Yadav
Pawan Yadav
Numerade Educator
01:32

Problem 31

a. Determine the dynamic (ac) resistance of the commercially available diode of Fig. 15 at a forward current of $10 \mathrm{~mA}$ using Eq. (5).
b. Determine the dynamic (ac) resistance of the diode of Fig. 15 at a forward current of $10 \mathrm{~mA}$ using Eq. (6).
c. Compare solutions of parts (a) and (b).

Aman Kumar
Aman Kumar
Numerade Educator
04:44

Problem 32

Using Eq. (5), determine the ac resistance at a current of $1 \mathrm{~mA}$ and $15 \mathrm{~mA}$ for the diode of Fig. 15. Compare the solutions and develop a general conclusion regarding the ac resistance and increasing levels of diode current.

Pawan Yadav
Pawan Yadav
Numerade Educator
04:44

Problem 33

Using Eq. (6), determine the ac resistance at a current of $1 \mathrm{~mA}$ and $15 \mathrm{~mA}$ for the diode of Fig.
15. Modify the equation as necessary for low levels of diode current. Compare to the solutions obtained in Problem 32 .

Pawan Yadav
Pawan Yadav
Numerade Educator
04:44

Problem 34

Determine the average ac resistance for the diode of Fig. 15 for the region between $0.6 \mathrm{~V}$ and $0.9 \mathrm{~V}$.

Pawan Yadav
Pawan Yadav
Numerade Educator
04:44

Problem 35

Determine the ac resistance for the diode of Fig. 15 at $0.75 \mathrm{~V}$ and compare it to the average ac resistance obtained in Problem 34 .

Pawan Yadav
Pawan Yadav
Numerade Educator
01:19

Problem 36

Find the piecewise-linear equivalent circuit for the diode of Fig. $15 .$ Use a straight-line segment that intersects the horizontal axis at $0.7 \mathrm{~V}$ and best approximates the curve for the region greater than $0.7 \mathrm{~V}$.

Narayan Hari
Narayan Hari
Numerade Educator
02:32

Problem 37

Repeat Problem 36 for the diode of Fig. $27 .$

Chai Santi
Chai Santi
Numerade Educator
01:19

Problem 38

Find the piecewise-linear equivalent circuit for the germanium and gallium arsenide diodes of Fig. 18 .

Narayan Hari
Narayan Hari
Numerade Educator
07:11

Problem 39

a. Referring to Fig. 33, determine the transition capacitance at reverse-bias potentials of $-25$ $V$ and $-10 \mathrm{~V}$. What is the ratio of the change in capacitance to the change in voltage?
b. Repeat part (a) for reverse-bias potentials of $-10 \mathrm{~V}$ and $-1 \mathrm{~V}$. Determine the ratio of the change in capacitance to the change in voltage.
c. How do the ratios determined in parts (a) and (b) compare? What does this tell you about which range may have more areas of practical application?

Meghan Miholics
Meghan Miholics
Numerade Educator
01:32

Problem 40

Referring to Fig. 33 , determine the diffusion capacitance at $0 \mathrm{~V}$ and $0.25 \mathrm{~V}$.

Vishnu P
Vishnu P
Numerade Educator
02:07

Problem 41

Describe in your own words how diffusion and transition capacitances differ.

Ameer Said
Ameer Said
Numerade Educator
03:01

Problem 42

Determine the reactance offered by a diode described by the characteristics of Fig. 33 at a forward potential of $0.2 \mathrm{~V}$ and a reverse potential of $-20 \mathrm{~V}$ if the applied frequency is $6 \mathrm{MHz}$.

Hubert Agamasu
Hubert Agamasu
Numerade Educator
01:52

Problem 43

The no-bias transition capacitance of a silicon diode is $8 \mathrm{pF}$ with $V_{K}=0.7 \mathrm{~V}$ and $n=1 / 2$. What is the transition capacitance if the applied reverse bias potential is $5 \mathrm{~V}$ ?

Chai Santi
Chai Santi
Numerade Educator
01:52

Problem 44

Find the applied reverse bias potential if the transition capacitance of a silicon diode is $4 \mathrm{pF}$ but the no-bias level is $10 \mathrm{pF}$ with $n=1 / 3$ and $V_{K}=0.7 \mathrm{~V}$.

Chai Santi
Chai Santi
Numerade Educator
03:25

Problem 45

Sketch the waveform for $i$ of the network of Fig. 57 if $t_{t}=2 t_{s}$ and the total reverse recovery time is $9 \mathrm{~ns}$.

Arpit Gupta
Arpit Gupta
Numerade Educator
01:56

Problem 46

Plot $I_{F}$ versus $V_{F}$ using linear scales for the diode of Fig. 37. Note that the provided graph employs a log scale for the vertical axis.

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
03:06

Problem 47

a. Comment on the change in capacitance level with increase in reverse-bias potential for the diode of Fig. 37 .
b. What is the level of $C(0)$ ?
c. Using $V_{K}=0.7 \mathrm{~V}$, find the level of $n$ in Eq. 9 .

Chai Santi
Chai Santi
Numerade Educator
03:01

Problem 48

Does the reverse saturation current of the diode of Fig. 37 change significantly in magnitude for reverse-bias potentials in the range $-25 \mathrm{~V}$ to $-100 \mathrm{~V}$ ?

Hubert Agamasu
Hubert Agamasu
Numerade Educator
02:19

Problem 49

For the diode of Fig. 37 determine the level of $I_{R}$ at room temperature $\left(25^{\circ} \mathrm{C}\right)$ and the boiling point of water $\left(100^{\circ} \mathrm{C}\right)$. Is the change significant? Does the level just about double for every $10{ }^{\circ} \mathrm{C}$ increase in temperature?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:35

Problem 50

For the diode of Fig. 37 , determine the maximum ac (dynamic) resistance at a forward current of $0.1,1.5$, and $20 \mathrm{~mA}$. Compare levels and comment on whether the results support conclusions derived in earlier sections of this chapter.

Sheh Lit Chang
Sheh Lit Chang
University of Washington
01:02

Problem 51

Using the characteristics of Fig. 37 , determine the maximum power dissipation levels for the diode at room temperature $\left(25^{\circ} \mathrm{C}\right)$ and $100^{\circ} \mathrm{C}$. Assuming that $V_{F}$ remains fixed at $0.7 \mathrm{~V}$, how has the maximum level of $I_{F}$ changed between the two temperature levels?

Kratika Bhadauria
Kratika Bhadauria
Numerade Educator
01:02

Problem 52

Using the characteristics of Fig. 37, determine the temperature at which the diode current will be $50 \%$ of its value at room temperature $\left(25^{\circ} \mathrm{C}\right)$.

Kratika Bhadauria
Kratika Bhadauria
Numerade Educator
01:56

Problem 53

The following characteristics are specified for a particular Zener diode: $V_{Z}=29 \mathrm{~V}, V_{R}=16.8 \mathrm{~V}$, $I_{Z T}=10 \mathrm{~mA}, I_{R}=20 \mu \mathrm{A}$, and $I_{Z M}=40 \mathrm{~mA} .$ Sketch the characteristic curve in the manner displayed in Fig. 47 .

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
01:13

Problem 54

At what temperature will the 10 - $V$ Zener diode of Fig. 47 have a nominal voltage of $10.75 \mathrm{~V}$ ?

Vinnu M
Vinnu M
Numerade Educator
01:02

Problem 55

Determine the temperature coefficient of a 5-V Zener diode (rated $25^{\circ} \mathrm{C}$ value) if the nominal voltage drops to $4.8 \mathrm{~V}$ at a temperature of $100{ }^{\circ} \mathrm{C}$.

Kratika Bhadauria
Kratika Bhadauria
Numerade Educator
01:02

Problem 56

Using the curves of Fig. 48a, what level of temperature coefficient would you expect for a 20-V diode? Repeat for a 5-V diode. Assume a linear scale between nominal voltage levels and a current level of $0.1 \mathrm{~mA}$.

Kratika Bhadauria
Kratika Bhadauria
Numerade Educator
02:33

Problem 57

Determine the dynamic impedance for the 24-V diode at $I_{Z}=10 \mathrm{~mA}$ for Fig. $48 \mathrm{~b}$. Note that it is a log scale.

Prachita Kush
Prachita Kush
Numerade Educator
03:56

Problem 58

Compare the levels of dynamic impedance for the $24-V$ diode of Fig. $48 b$ at current levels of $0.2,1$, and $10 \mathrm{~mA}$. How do the results relate to the shape of the characteristics in this region?

Chai Santi
Chai Santi
Numerade Educator
02:01

Problem 59

Referring to Fig. $52 \mathrm{e}$, what would appear to be an appropriate value of $V_{K}$ for this device? How does it compare to the value of $V_{K}$ for silicon and germanium?

Chai Santi
Chai Santi
Numerade Educator
02:29

Problem 60

Given that $E_{g}=0.67 \mathrm{eV}$ for germanium, find the wavelength of peak solar response for the material. Do the photons at this wavelength have a lower or higher energy level?

Suzanne W.
Suzanne W.
Numerade Educator
04:44

Problem 61

Using the information provided in Fig. 52, determine the forward voltage across the diode if the relative luminous intensity is $1.5$.

Pawan Yadav
Pawan Yadav
Numerade Educator
View

Problem 62

a. What is the percentage increase in relative efficiency of the device of Fig. 52 if the peak current is increased from $5 \mathrm{~mA}$ to $10 \mathrm{~mA}$ ?
b. Repeat part (a) for $30 \mathrm{~mA}$ to $35 \mathrm{~mA}$ (the same increase in current).
c. Compare the percentage increase from parts (a) and (b). At what point on the curve would you say there is little to be gained by further increasing the peak current?

Amit Srivastava
Amit Srivastava
Numerade Educator
01:43

Problem 63

a. If the luminous intensity at $0^{\circ}$ angular displacement is $3.0 \mathrm{mcd}$ for the device of Fig. 52, at what angle will it be $0.75 \mathrm{mcd}$ ?
b. At what angle does the loss of luminous intensity drop below the $50 \%$ level?

Suhas Katkar
Suhas Katkar
Numerade Educator
02:41

Problem 64

Sketch the current derating curve for the average forward current of the high-efficiency red LED of Fig. 52 as determined by temperature. (Note the absolute maximum ratings.)

Anurag Kumar
Anurag Kumar
Numerade Educator