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Electronic Devices and Circuit Theory

Robert Boylestad, Louis Nashelsky

Chapter 16

Other Two-Terminal Devices - all with Video Answers

Educators

Chapter Questions

00:39

Problem 1

a. Describe in your own words how the construction of the hot-carrier diode is significantly different from the conventional semiconductor diode.
b. In addition, describe its mode of operation.

Manish Kumar
Manish Kumar
Numerade Educator
01:39

Problem 2

a. Consult Fig. 2. Compare the dynamic resistances of the diodes in the forward-bias regions.
b. How do the levels of $I_{s}$ and $V_{Z}$ compare?

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
03:56

Problem 3

Using the data of Fig. 5, determine the reverse leakage current at a temperature of $50^{\circ} \mathrm{C}$. Assume a linear relationship between the two quantities.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
08:21

Problem 4

(a) Using the electrical characteristics of Fig. 5, find the reactance of the capacitor at a frequency of $1 \mathrm{MHz}$ and a reverse voltage of $1 \mathrm{~V}$. (b) Find the forward dc resistance of the diode at $10 \mathrm{~mA}$.
5. a. Using the data from Fig. 5 plot the forward current versus forward voltage for the Schottky diode.
b. Determine the piecewise equivalent resistance for the vertical rise section of the characteristics.
c. What is the resulting vertical break voltage for the diode as compared to the $0.7 \mathrm{~V}$ value typically used for a $p-n$ junction diode.
6. Using the plot of Fig. 6a,
a. What is the forward voltage at a current of $50 \mathrm{~mA}$ (note the log scale) at room temperature $\left(25^{\circ} \mathrm{C}\right)$
b. What is the forward voltage at the same current as part (a) but a temperature of $125^{\circ} \mathrm{C}$ ?
c. What can be said about the effect of temperature on the resulting voltage drop across a Schottky diode as the temperature increases?

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
03:51

Problem 5

(a) Using the electrical characteristics of Fig. 5, find the reactance of the capacitor at a frequency of $1 \mathrm{MHz}$ and a reverse voltage of $1 \mathrm{~V}$. (b) Find the forward dc resistance of the diode at $10 \mathrm{~mA}$.

Zulfiqar Ali
Zulfiqar Ali
Numerade Educator
01:04

Problem 6

Using the plot of Fig. 6a,
a. What is the forward voltage at a current of $50 \mathrm{~mA}$ (note the log scale) at room temperature $\left(25^{\circ} \mathrm{C}\right)$
b. What is the forward voltage at the same current as part (a) but a temperature of $125^{\circ} \mathrm{C}$ ?
c. What can be said about the effect of temperature on the resulting voltage drop across a Schottky diode as the temperature increases?

Mayukh Banik
Mayukh Banik
Numerade Educator
03:51

Problem 7

Using the characteristics of Fig. $6(\mathrm{c})$, determine the reactance of the diode capacitor at a frequency of $1 \mathrm{MHz}$ and a reverse bias potential of $1 \mathrm{~V}$. Is it significant?

Zulfiqar Ali
Zulfiqar Ali
Numerade Educator
01:28

Problem 8

a. Determine the transition capacitance of a diffused junction varicap diode at a reverse potential of $4.2 \mathrm{~V}$ if $C(0)=80 \mathrm{pF}$ and $V_{r}=0.7 \mathrm{~V}$
b. From the information of part (a), determine the constant $K$ in Eq. (2).

Chai Santi
Chai Santi
Numerade Educator
01:39

Problem 9

a. For a varicap diode having the characteristics of Fig. 7 , determine the difference in capacitance between reverse-bias potentials of $-3 \mathrm{~V}$ and $-12 \mathrm{~V}$.
b. Determine the incremental rate of change $\left(\Delta C / \Delta V_{r}\right)$ at $V=-8 \mathrm{~V} .$ How does this value compare with the incremental change determined at $-2 \mathrm{~V}$ ?

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
02:30

Problem 10

Using Fig. 10a, determine the total capacitance at a reverse potential of $1 \mathrm{~V}$ and $8 \mathrm{~V}$ and find the tuning ratio between these two levels. How does it compare to the tuning ratio for the ratio between reverse bias potentials of $1.25 \mathrm{~V}$ and $7 \mathrm{~V}$ ?

Dwijendra Rao
Dwijendra Rao
Numerade Educator
01:26

Problem 11

At a reverse-bias potential of $4 \mathrm{~V}$, determine the total capacitance for the varactor from Fig. $10 \mathrm{a}$ and calculate the $Q$ value from $Q=1 /\left(2 \pi f R_{S} C_{t}\right)$ using a frequency of $10 \mathrm{MHz}$ and $R_{s}=3 \Omega$. Compare to the $Q$ value determined from the chart of Fig. 10a.

Kratika Bhadauria
Kratika Bhadauria
Numerade Educator
01:02

Problem 12

Determine $T_{1}$ for a varactor diode if $C_{0}=22 \mathrm{pF}, T C_{C}=0.02 \% /{ }^{\circ} \mathrm{C}$, and $\Delta C=0.11 \mathrm{pF}$ due to an increase in temperature above $T_{0}=25^{\circ} \mathrm{C}$.

Kratika Bhadauria
Kratika Bhadauria
Numerade Educator
01:57

Problem 13

What region of $V_{R}$ would appear to have the greatest change in capacitance per change in reverse voltage for the diode of Fig. $10 ?$ Be aware that it is a log-log scale. Then, for this region, determine the ratio of the change in capacitance to the change in voltage.

Narayan Hari
Narayan Hari
Numerade Educator
02:58

Problem 14

Using Fig. 10a, compare the $Q$ levels at a reverse bias potential of $1 \mathrm{~V}$ and $10 \mathrm{~V}$. What is the ratio between the two? If the resonant frequency is $10 \mathrm{MHz}$, what is the bandwidth for each bias voltage? Compare the bandwidths obtained and compare their ratio to the ratio of $Q$ levels.

Narayan Hari
Narayan Hari
Numerade Educator
02:49

Problem 15

Referring to Fig. 11, if $V_{D D}=2 \mathrm{~V}$ for the varactor of Fig. 10, find the resonant frequency of the tank circuit if $C_{C}=40 \mathrm{pF}$ and $L_{T}=2 \mathrm{mH}$.

Amit Srivastava
Amit Srivastava
Numerade Educator
03:58

Problem 16

A $1-\mathrm{cm}$ by $2-\mathrm{cm}$ solar cell has a conversion efficiency of $9 \%$. Determine the maximum power rating of the device.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:12

Problem 17

If the power rating of a solar cell is determined on a very rough scale by the product $V_{O C} I_{S C}$, is the greatest rate of increase obtained at lower or higher levels of illumination? Explain your reasoning.

Manish Kumar
Manish Kumar
Numerade Educator
02:22

Problem 18

a. For the solar cell of Fig. 13, determine the ratio $\Delta I_{S C} / \Delta f c$ if $f c_{1}=20 f$.
b. Using the results of part (a), find the level of $I_{S C}$ resulting from a light intensity of 28 footcandles.

Olivier Anderson
Olivier Anderson
Numerade Educator
02:09

Problem 19

a. For the solar cell of Fig. 14, determine the ratio $\Delta I V_{O C} / \Delta f_{c}$ for the range of $20 f c$ to $100 f c$ if $f c_{1}=40 f c$
b. Using the results of part (a), determine the expected level of $V_{O C}$ at a light intensity of $60 \mathrm{fc}$.

Chai Santi
Chai Santi
Numerade Educator
03:09

Problem 20

a. Plot the $1-V$ curve for the same solar cell of Fig. 15 but with a light intensity of $f c_{1}$.
b. Plot the resulting power curve from the results of part (a).
c. What is the maximum power rating? How dews it compare to the maximum power rating for a light intensity $f c_{2}$ ?

Donald Albin
Donald Albin
Numerade Educator
01:51

Problem 21

a. What is the energy in joules associated with photons that have a wavelength matching that of the color blue in the visible spectrum?
b. Repeat part (a) for the color red.
c. Do the results confirm the fact that the shorter the wavelength the higher the energy level?
d. Is light in the ultraviolet range more dangerous in regard to skin cancer than those in the infrared range? Why?
e. Can you guess why fluorescent lights are used for growing plants in a dark environment?

Sheh Lit Chang
Sheh Lit Chang
University of Washington
01:27

Problem 22

Referring to Fig. 20 , determine $I_{\lambda}$ if $V_{\lambda}=30 \mathrm{~V}$ and the light intensity is $4 \times 10^{-9} \mathrm{~W} / \mathrm{m}^{2}$.

Mirza Aslam Beig
Mirza Aslam Beig
Numerade Educator
01:31

Problem 23

Determine the voltage drop across the resistor of Fig. 19 if the incident flux is $3000 \mathrm{fc}$, $V_{\lambda}=25 \mathrm{~V}$, and $R=100 \mathrm{k} \Omega$. Use the characteristics of Fig. $20 .$

Mirza Aslam Beig
Mirza Aslam Beig
Numerade Educator
02:16

Problem 24

Write an equation for the diode current of Fig. 22 versus the applied light intensity in footcandles.

Narayan Hari
Narayan Hari
Numerade Educator
05:05

Problem 25

What is the approximate rate of change of resistance with illumination for a photoconductive cell with the characteristics of Fig. 26 for the ranges (a) $0.1 \rightarrow 1 \mathrm{k} \Omega$, (b) $1 \rightarrow 10 \mathrm{k} \Omega$, and (c) $10 \rightarrow \mathrm{k} \Omega ?$ (Note that this is a log scale.) Which region has the greatest rate of change in resistance with illumination?

Vishal Gupta
Vishal Gupta
Numerade Educator
00:26

Problem 26

What is the "dark current" of a photodiode?

Mayukh Banik
Mayukh Banik
Numerade Educator
02:01

Problem 27

If the illumination on the photoconductive diode in Fig. 28 is $10 \mathrm{fc}$, determine the magnitude of $V_{i}$ to establish $6 \mathrm{~V}$ across the cell if $R_{1}$ is equal to $5 \mathrm{k} \Omega$. Use the characteristics of Fig. 26 .

Vinnu M
Vinnu M
Numerade Educator
02:06

Problem 28

Using the data provided in Fig. 27 , sketch a curve of percentage conductance versus temperature for $0.01,1.0$, and $100 \mathrm{fc}$. Are there any noticeable effects?

Kaden Hamblin
Kaden Hamblin
Numerade Educator
03:43

Problem 29

a. Sketch a curve of rise time versus illumination using the data from Fig. 27 .
b. Repeat part (a) for the decay time.
c. Discuss any noticeable effects of illumination in parts (a) and (b).

Asma Venkitta
Asma Venkitta
Numerade Educator
00:46

Problem 30

Which colors is the CdS unit of Fig. 27 most sensitive to?

Emily Marty
Emily Marty
Numerade Educator
01:45

Problem 31

a. Determine the radiant flux at a dc forward current of $70 \mathrm{~mA}$ for the device of Fig. $30 .$
b. Determine the radiant flux in lumens at a dc forward current of $45 \mathrm{~mA}$.

Anurag Kumar
Anurag Kumar
Numerade Educator
03:13

Problem 32

a. Through the use of Fig. 31 , determine the relative radiant intensity at an angle of $25^{\circ}$ for a package with a flat glass window.
b. Plot a curve of relative radiant intensity versus degrees for the flat package.

Shoukat Ali
Shoukat Ali
Other Schools
01:05

Problem 33

If $60 \mathrm{~mA}$ of dc forward current is applied to an SG1010A IR emitter, what will be the incident radiant flux in lumens $5^{\circ}$ off the center if the package has an internal collimating system? Refer to Figs. 30 and 31 .

Narayan Hari
Narayan Hari
Numerade Educator
09:48

Problem 34

Referring to Fig. 35, which terminals must be energized to display number 7 ?

Sikandar Baig
Sikandar Baig
Numerade Educator
09:48

Problem 35

Referring to Fig. 35, which terminals must be energized to display number 7 ?

Sikandar Baig
Sikandar Baig
Numerade Educator
03:49

Problem 36

Discuss the relative differences in mode of operation between an LED and an LCD display.

AG
Ankit Gupta
Numerade Educator
00:44

Problem 37

What are the relative advantages and disadvantages of an LCD display as compared to an LED display?

Jorge Villanueva
Jorge Villanueva
Numerade Educator
08:43

Problem 38

For the thermistor of Fig. 40 , determine the dynamic rate of change in specific resistance with temperature at $T=20^{\circ} \mathrm{C}$. How does this compare to the value determined at $T=300^{\circ} \mathrm{C}$ ? From the results, determine whether the greatest change in resistance per unit change in temperature occurs at lower or higher levels of temperature. Note the vertical log scale.

Marcella Sippey
Marcella Sippey
Numerade Educator
03:11

Problem 39

Using the information provided in Fig. 40 , determine the total resistance of a $2-\mathrm{cm}$ length of the material having a perpendicular surface area of $1 \mathrm{~cm}^{2}$ at a temperature of $0^{\circ} \mathrm{C}$. Note the vertical log scale.

Charles Machakwa
Charles Machakwa
Numerade Educator
07:32

Problem 40

a. Referring to Fig. 41 , determine the current at which a $25^{\circ} \mathrm{C}$ sample of the material changes from a positive to a negative temperature coefficient. (Figure 41 is a log scale.)
b. Determine the power and resistance levels of the device (Fig. 41) at the peak of the $0{ }^{\circ} \mathrm{C}$ curve.
c. At a temperature of $25^{\circ} \mathrm{C}$, determine the power rating if the resistance level is $1 \mathrm{M} \Omega$.

Yaqub Khan
Yaqub Khan
Numerade Educator
01:14

Problem 41

In Fig. $43, V=0.2 \mathrm{~V}$ and $R_{\text {variable }}=10 \Omega$. If the current through the sensitive movement is 2 $\mathrm{mA}$ and the voltage drop across the movement is $0 \mathrm{~V}$, what is the resistance of the thermistor?

Narayan Hari
Narayan Hari
Numerade Educator
00:39

Problem 42

What are the essential differences between a semiconductor junction diode and a tunnel diode?

Manish Kumar
Manish Kumar
Numerade Educator
02:23

Problem 43

Note in the equivalent circuit of Fig. 45 that the capacitor appears in parallel with the negative resistance. Determine the reactance of the capacitor at $1 \mathrm{MHz}$ and $100 \mathrm{MHz}$ if $C=5 \mathrm{pF}$, and determine the total impedance of the parallel combination (with $R=-152 \Omega$ ) at each frequency. Is the magnitude of the inductive reactance anything to be overly concerned about at either of these frequencies if $L_{S}=6 \mathrm{nH}$ ?

Narayan Hari
Narayan Hari
Numerade Educator
03:56

Problem 44

Why do you believe the maximum reverse current rating for the tunnel diode can be greater than the forward current rating? (Hint: Note the characteristics and consider the power rating.)

Chai Santi
Chai Santi
Numerade Educator
03:01

Problem 45

Determine the negative resistance for the tunnel diode of Fig. 44 between $V_{T}=0.1 \mathrm{~V}$ and $V_{T}$ $=0.3 \mathrm{~V}$
.

Hubert Agamasu
Hubert Agamasu
Numerade Educator
08:56

Problem 46

Determine the stable operating points for the network of Fig. 48 if $E=2 \mathrm{~V}, R=0.39 \mathrm{k} \Omega$, and the tunnel diode of Fig. 44 is employed.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
00:59

Problem 47

For $E=0.5 \mathrm{~V}$ and $R=51 \Omega$, sketch $v_{T}$ for the network of Fig. 49 and the tunnel diode of Fig. $44 .$

Chai Santi
Chai Santi
Numerade Educator
02:16

Problem 48

Determine the frequency of oscillation for the network of Fig. 50 if $L=5 \mathrm{mH}, R_{1}=10 \Omega$, and $C=1 \mu \mathrm{F}$.

Shahab Ullah
Shahab Ullah
Numerade Educator