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Electronic Devices and Circuit Theory

Robert Boylestad, Louis Nashelsky

Chapter 9

BJT and JFET Frequency Response - all with Video Answers

Educators

Chapter Questions

05:34

Problem 1

a. Determine the common logarithm of the following numbers: $10^{3}, 50$, and $0.707$.
b. Determine the natural logarithm of the numbers appearing in part (a).
c. Comnare the solutions of narts $(a)$ and $(b)$

Madysn Cardinal
Madysn Cardinal
Numerade Educator
03:16

Problem 2

a. Determine the common logarithm of the number $0.24 \times 10^{6}$.
b. Determine the natural logarithm of the number of part (a) using Eq. (4).
c. Determine the natural logarithm of the number of part (a) using natural logarithms and compare with the solution of part (b).

Anas Venkitta
Anas Venkitta
Numerade Educator
00:44

Problem 3

Determine:
a. $20 \log _{10}\left(\frac{84}{6}\right)$ using Eq. (6) and compare with $20 \log _{10} 14$.
b. $10 \log _{10}\left(\frac{1}{250}\right)$ using Eq. (7) and compare with $10 \log _{10} 4 \times 10^{-3}$.
c. $\log _{10}(40)(0.2)$ using Eq. (8) and compare with $\log _{10} 8$.

AG
Ankit Gupta
Numerade Educator
03:36

Problem 4

Calculate the power gain in decibels for each of the following cases.
a. $P_{o}=100 \mathrm{~W}, P_{i}=5 \mathrm{~W}$.
b. $P_{o}=100 \mathrm{~mW}, P_{i}=5 \mathrm{~mW}$.
c. $P_{o}=100 \mathrm{~mW}, P_{i}=20 \mu \mathrm{W}$.

Anas Venkitta
Anas Venkitta
Numerade Educator
02:33

Problem 5

Determine $G_{\mathrm{dBm}}$ for an output power level of $25 \mathrm{~W}$.

Prabhat Tyagi
Prabhat Tyagi
Numerade Educator
01:04

Problem 6

Two voltage measurements made across the same resistance are $V_{1}=110 \mathrm{~V}$ and $V_{2}=220 \mathrm{~V}$. Calculate the power gain in decibels of the second reading over the first reading.

Christopher Stanley
Christopher Stanley
Numerade Educator
01:04

Problem 7

Input and output voltage measurements of $V_{i}=10 \mathrm{mV}$ and $V_{o}=25 \mathrm{~V}$ are made. What is the voltage gain in decibels?

Christopher Stanley
Christopher Stanley
Numerade Educator
02:10

Problem 8

a. The total decibel gain of a three-stage system is $120 \mathrm{~dB}$. Determine the decibel gain of each stage if the second stage has twice the decibel gain of the first and the third has $2.7$ times the decibel gain of the first.
b. Determine the voltage gain of each stage.

Kajal Gautam
Kajal Gautam
Numerade Educator
01:42

Problem 9

If the applied ac power to a system is $5 \mu \mathrm{W}$ at $100 \mathrm{mV}$ and the output power is $48 \mathrm{~W}$. determine:
a. The power gain in decibels.
b. The voltage gain in decibels if the output impedance is $40 \mathrm{k} \Omega$.
c. The input impedance.
d. The output voltage.

Christopher Stanley
Christopher Stanley
Numerade Educator
02:20

Problem 10

Given the characteristics of Fig. 78 , sketch:
a. The normalized gain.
b. The normalized dB gain (and determine the bandwidth and cutoff frequencies).

Amit Srivastava
Amit Srivastava
Numerade Educator
02:51

Problem 11

For the network of Fig. 79 :
a. Determine the mathematical expression for the magnitude of the ratio $V_{o} / V_{i}$.
b. Using the results of part (a), determine $V_{o} / V_{i}$ at $100 \mathrm{~Hz}, 1 \mathrm{kHz}, 2 \mathrm{kHz}, 5 \mathrm{kHz}$, and $10 \mathrm{kHz}$, and plot the resulting curve for the frequency range of $100 \mathrm{~Hz}$ to $10 \mathrm{kHz}$. Use a log scale.
c. Determine the break frequency.
d. Sketch the asymptotes and locate the $-3-\mathrm{dB}$ point.
e. Sketch the frequency response for $V_{o} / V_{i}$ and compare to the results of part (b).

Zulfiqar Ali
Zulfiqar Ali
Numerade Educator
08:54

Problem 12

For the network of Fig. 79 :
a. Determine the mathematical expression for the angle by which $V_{o}$ leads $V_{i}$.
b. Determine the phase angle at $f=100 \mathrm{~Hz}, 1 \mathrm{kHz}, 2 \mathrm{kHz}, 5 \mathrm{kHz}$, and $10 \mathrm{kHz}$, and plot the resulting curve for the frequency range of $100 \mathrm{~Hz}$ to $10 \mathrm{kHz}$.
c. Determine the break frequency.
d. Sketch the frequency response of $\theta$ for the frequency spectrum of part (b) and compare results.

Linda Winkler
Linda Winkler
Numerade Educator
01:01

Problem 13

a. What frequency is one octave above $5 \mathrm{kHz}$ ?
b. What frequency is one decade below $10 \mathrm{kHz}$ ?
c. What frequency is two octaves below $20 \mathrm{kHz}$ ?
d. What frequency is two decades above $1 \mathrm{kHz}$ ?

Narayan Hari
Narayan Hari
Numerade Educator
01:24

Problem 14

Repeat the analysis of Example 11 with $r_{o}=40 \mathrm{k} \Omega$. What is the effect on $A_{v_{\text {mid }}}, f_{L_{S}}, f_{L_{C}}, f_{L_{E}}$, and the resulting cutoff frequency?

Amit Srivastava
Amit Srivastava
Numerade Educator
00:55

Problem 15

For the network of Fig. 80 :
a. Determine $r_{e}$
b. Find $A_{v_{\text {mid }}}=V_{o} / V_{i}$.
c. Calculate $Z_{i}$.
d. Determine $f_{L_{S}}, f_{L_{C}}$, and $f_{L_{E}}$
e. Determine the low cutoff frequency.
f. Sketch the asymptotes of the Bode plot defined by the cutoff frequencies of part (d).
g. Sketch the low-frequency response for the amplifier using the results of part (e).

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
02:20

Problem 16

Repeat Problem 15 for the emitter-stabilized network of Fig. 81 .

Netra Sharma
Netra Sharma
University of Wisconsin - Milwaukee
01:22

Problem 17

Repeat Problem 15 for the emitter-follower network of Fig. 82 .

Raj Bala
Raj Bala
Numerade Educator
05:37

Problem 18

Repeat Problem 15 for the common-base configuration of Fig. $83 .$ Keep in mind that the common-base configuration is a noninverting network when you consider the Miller effect.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
02:58

Problem 19

Repeat the analysis of problem 15 for the network of Fig. 80 with the addition of a source resistance and signal source as shown in Fig. 84. Plot the gain $A_{v_{s}}=\frac{V_{o}}{V_{s}}$ and comment on the change in low-frequency cutoff as compared to problem $15 .$

Narayan Hari
Narayan Hari
Numerade Educator
02:58

Problem 20

Repeat the analysis of problem 15 for the network of Fig. 81 with the addition of a source resistance and signal source as shown in Fig. $85 .$ Plot the gain $A_{v_{s}}=\frac{V_{o}}{V_{s}}$ and comment on the change in low-frequency cutoff as compared to problem 16 .

Narayan Hari
Narayan Hari
Numerade Educator
03:00

Problem 21

Repeat the analysis of problem 15 for the network of Fig. 82 with the addition of a source resistance and signal source as shown in Fig. 86. Plot the gain $A_{v_{s}}=\frac{V_{o}}{V_{s}}$ and comment on the change in low-frequency cutoff as compared to problem 17 .

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
03:00

Problem 22

Repeat the analysis of problem 15 for the network of Fig. 83 with the addition of a source resistance and signal source as shown in Fig. 87 . Plot the gain $A_{v_{s}}=\frac{V_{o}}{V_{s}}$ and comment on the change in low-frequency cutoff as compared to problem 18 .

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
05:46

Problem 23

For the network of Fig. 88 :
a. Determine $V_{G S_{Q}}$ and $I_{D_{Q}}$.
b. Find $g_{m 0}$ and $g_{m}$.
c. Calculate the midband gain of $A_{v}=V_{o} / V_{i}$.
d. Determine $Z_{i}$.
e. Calculate $A_{v_{s}}=V_{o} / V_{s}$.
f. Determine $f_{L_{G}}, f_{L_{C}}$, and $f_{L_{S}}$.
g. Determine the low-cutoff frequency.
h. Sketch the asymptotes of the Bode plot defined by part (f).
i. Sketch the low-frequency response for the amplifier using the results of part (f).

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
01:21

Problem 24

Repeat the analysis of Problem 23 with $r_{d}=100 \mathrm{k} \Omega$. Does it have an effect of any consequence on the results? If so, which elements?

Kajal Gautam
Kajal Gautam
Numerade Educator
01:41

Problem 25

Repeat the analysis of Problem 23 for the network of Fig. $89 .$ What effect does the voltagedivider configuration have on the input impedance and the gain $A_{v_{s}}$ compared to the biasing arrangement of Fig. 88 ?

Narayan Hari
Narayan Hari
Numerade Educator
01:09

Problem 26

a. The feedback capacitance of an inverting amplifier is $10 \mathrm{pF}$. What is the Miller capacitance at the input if the gain of the amplifier is $-120$ ?
b. What is the Miller capacitance at the output of the amplifier?
c. Is it a good approximation to assume $C_{M_{i}} \cong\left|A_{v}\right| C_{f}$ and $C_{M_{o}} \cong C_{f} ?$

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
01:47

Problem 27

For the network of Fig. 80 with $R_{s}$ and $V_{s}$ of Fig. 84 :
a. Determine $f_{H_{i}}$ and $f_{H_{o}}$.
b. Find $f_{\beta}$ and $f_{T}$.
c. Sketch the frequency response for the high-frequency region using a Bode plot and determine the cutoff frequency.
d. What is the gain-bandwidth product of the amplifier?

Amit Srivastava
Amit Srivastava
Numerade Educator
05:37

Problem 28

Repeat the analysis of Problem 27 for the network of Fig. 81 with $R_{s}$ and $V_{s}$ of Fig. 85 .

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
05:37

Problem 29

Repeat the analysis of Problem 27 for the network of Fig. 82 with $R_{s}$ and $V_{s}$ of Fig. 86 .

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
05:37

Problem 30

Repeat the analysis of Problem 27 for the network of Fig. 83 with $R_{s}$ and $V_{s}$ of Fig. 87 .

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
03:51

Problem 31

For the network of Fig. 88 :
a. Determine $g_{m_{0}}$ and $g_{m}$.
b. Find $A_{v}$ and $A_{v_{s}}$ in the mid-frequency range.
c. Determine $f_{H_{i}}$ and $f_{H_{o}}$.
d. Sketch the frequency response for the high-frequency region using a Bode plot and determine the cutoff frequency.
e. What is the gain-bandwidth product of the amplifier?

M Hassan Anwar
M Hassan Anwar
Numerade Educator
02:20

Problem 32

Repeat the analysis of Problem 31 for the network of Fig. $89 .$

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
02:10

Problem 33

Calculate the overall voltage gain of four identical stages of an amplifier, each having a gain of 20 .

Kajal Gautam
Kajal Gautam
Numerade Educator
01:31

Problem 34

Calculate the overall upper $3-\mathrm{dB}$ frequency for a four-stage amplifier having an individual stage value of $f_{2}=2.5 \mathrm{MHz}$

Narayan Hari
Narayan Hari
Numerade Educator
01:31

Problem 35

A four-stage amplifier has a lower $3-\mathrm{dB}$ frequency for an individual stage of $f_{1}=40 \mathrm{~Hz}$. What is the value of $f_{1}$ for this full amplifier?

Narayan Hari
Narayan Hari
Numerade Educator
03:41

Problem 36

The application of a $10-\mathrm{mV}, 100-\mathrm{kHz}$ square wave to an amplifier resulted in the output waveform of Fig. 90 .
a. Write the Fourier series expansion for the square wave through the ninth harmonic.
b. Determine the bandwidth of the amplifier to the accuracy available by the waveform of Fig. 90 .
c. Calculate the low-cutoff frequency

Sachin Rao
Sachin Rao
Numerade Educator
02:18

Problem 37

Using PSpice Windows, determine the frequency response of $V_{o} / V_{i}$ for the high-pass filter of Fig. 45 of $R=8.2 \mathrm{k} \Omega$ and $C=4.7 \mu \mathrm{F}$.

Ajay Singhal
Ajay Singhal
Numerade Educator
02:35

Problem 38

Using PSpice Windows, determine the frequency response of $V_{o} / V_{s}$ for the BJT amplifier of Fig. 87 .

Kajal Gautam
Kajal Gautam
Numerade Educator
02:22

Problem 39

Repeat Problem 38 for the network of Fig. 83 using Multisim.

Chai Santi
Chai Santi
Numerade Educator
02:10

Problem 40

Repeat Problem 38 for the JFET configuration of Fig. 88 using Multisim.

Chai Santi
Chai Santi
Numerade Educator