# Boylestad: MCQ in Bipolar Junction Transistor Amplifiers

(Last Updated On: December 2, 2019) This is the Multiple Choice Questions in Bipolar Junction Transistor Amplifiers from the book Electronic Devices and Circuit Theory 10th Edition by Robert L. Boylestad. If you are looking for a reviewer in Electronics Engineering this will definitely help. I can assure you that this will be a great help in reviewing the book in preparation for your Board Exam. Make sure to familiarize each and every questions to increase the chance of passing the ECE Board Exam.

#### Online Questions and Answers Topic Outline

• MCQ in BJT Amplifiers
• MCQ in Amplifier Operation
• MCQ in Transistor AC Models
• MCQ in The Common-Emitter Amplifier
• MCQ in The Common-Collector Amplifier
• MCQ in The Common-Base Amplifier
• MCQ in Multistage Amplifiers
• MCQ in The Differential Amplifier
• MCQ in Common mode
• MCQ in CMRR (Common-mode rejection ratio)
• MCQ in Emitter-follower
• MCQ in AC Quantities

#### Practice Exam Test Questions

Choose the letter of the best answer in each questions.

1. Which of the following techniques can be used in the sinusoidal ac analysis of transistor networks?

A) Small-signal

B) Large-signal

C) Small- or large-signal

D) None of the above

Solution:

2. What is the limit of the efficiency defined by = Po/Pi?

A) Greater than 1

B) Less than 1

C) Always 1

D) None of the above

Solution:

3. Which of the following define(s) the conversion efficiency?

A) Ac power to the load/ac input power

B) Ac power to the load/dc power supplied

C) Dc output power/ac input power

D) All of the above

Solution:

4. Which of the following should be done to obtain the ac equivalent of a network?

A) Set all dc sources to zero

B) Replace all capacitors by a short-circuit equivalent.

C) Remove all elements bypassed by the short-circuit equivalent.

D) All of the above

Solution:

5. The ______ model suffers from being limited to a particular set of operating conditions if it is to be considered accurate.

A) hybrid equivalent

B) re

C) β

D) Thevenin

Solution:

6. The ______ model fails to account for the output impedance level of the device and the feedback effect from output to input.

A) hybrid equivalent

B) re

C) β

D) Thevenin

Solution:

7. Which of the following is (are) true regarding the input impedance for frequencies in the midrange ≤ 100 kHz of a BJT transistor amplifier?

A) The input impedance is purely resistive.

B) It varies from a few ohms to mega ohms.

C) An ohmmeter cannot be used to measure the small-signal ac input impedance.

D) All of the above

Solution:

8. Which of the following is (are) true regarding the output impedance for frequencies in the midrange ≤ 100 kHz of a BJT transistor amplifier?

A) The output impedance is purely resistive.

B) It varies from a few ohms to more than 2 MΩ.

C) An ohmmeter cannot be used to measure the small-signal ac output impedance.

D) All of the above

Solution:

9. What is the range of the current gain for BJT transistor amplifiers?

A) less than 1

B) 1 to 100

C) above 100

D) All of the above

Solution:

10. The input impedance of a BJT amplifier is purely ______ in nature and can vary from a few ______ to ______.

A) resistive, ohms, megohms

C) inductive, millihenrys, henrys

D) None of the above

Solution:

11. For BJT amplifiers, the _______ gain typically ranges from a level just less than 1 to a level that may exceed 1000.

A) voltage

B) current

C) impedance

D) All of the above

Solution:

12. What is the unit of the parameter ho?

A) Volt

B) Ohm

C) Siemen

D) No unit

Solution:

13. Which of the h-parameters corresponds to re in a common-base configuration?

A) hib

B) hfb

C) hrb

D) hob

Solution:

14. What is the range of the input impedance of a common-base configuration?

A) A few ohms to a maximum of 50 Ω

B) 1 kΩ to 5 kΩ

C) 100 kΩ to 500 kΩ

D) 1 MΩ to 2 MΩ

Solution:

15. What is the typical value of the current gain of a common-base configuration?

A) Less than 1

B) Between 1 and 50

C) Between 100 and 200

D) Undefined

Solution:

16. What is the controlling current in a common-base configuration?

A) Ie

B) Ic

C) Ib

D) None of the above

Solution:

17. What is the typical range of the output impedance of a common-emitter configuration?

A) 10 Ω to 100 Ω

B) 1 kΩ to 5 kΩ

C) 40 kΩ to 50 kΩ

D) 500 kΩ to 1 MΩ

Solution:

18. Under which of the following conditions is the output impedance of the network approximately equal to RC for a common-emitter fixed-bias configuration?

A) ro ≥ 10RC

B) ro < 10RC

C) re < ro

D) re > ro

Solution:

19. Under which of the following condition(s) is the current gain Av ≈ β?

A) ro ≥ 10RC

B) RB ≥ 10re

C) ro ≥ 10RC and RB ≥ 10re

D) None of the above

Solution:

20. What does the negative sign in the voltage gain of the common-emitter fixed-bias configuration indicate?

A) The output and input voltages are 180° out of phase.

B) Gain is smaller than 1.

C) Gain is larger than 1.

D) None of the above

Solution:

21. For the common-emitter fixed-bias configuration, there is a _____ phase shift between the input and output signals.

A) 0°

B) 45°

C) 90°

D) 180°

Solution:

22. Which of the following configurations has an output impedance Zo equal to RC?

A) Fixed-bias common-emitter

B) Common-emitter voltage-divider with bypass capacitor

C) Common-emitter voltage-divider without bypass capacitor

D) All of the above

Solution:

23. Which of the following configurations has a voltage gain of –RC /re?

A) Fixed-bias common-emitter

B) Common-emitter voltage-divider with bypass capacitor

C) Fixed-bias common-emitter and voltage-divider with bypass capacitor

D) Common-emitter voltage-divider without bypass capacitor

Solution:

24. Which of the following configurations has the lowest output impedance?

A) Fixed-bias

B) Voltage-divider

C) Emitter-follower

D) None of the above

Solution:

25. The ________ configuration is frequently used for impedance matching.

A) fixed-bias

B) voltage-divider bias

C) emitter-follower

D) collector feedback

Solution:

26. The emitter-follower configuration has a ______ impedance at the input and a ______ impedance at the output.

A) low, low

B) low, high

C) high, low

D) high, high

Solution:

27. Which of the following gains is less than 1 for a common-base configuration?

A) Ai

B) Av

C) Ap

D) None of the above

Solution:

28. Which of the following conditions must be met to allow the use of the approximate approach in a voltage-divider bias configuration?

A) βre > 10R2

B) βRE > 10R2

C) βRE < 10R2

D) βre < 10R2

Solution:

29. Which one of the following configurations has the lowest input impedance?

A) Fixed-bias

B) Common-base

C) Emitter-follower

D) Voltage-divider?

Solution:

30. For the collector dc feedback configuration, there is a _____ phase shift between the input and output signals.

A) 0°

B) 45°

C) 90°

D) 180°

Solution:

31. Which of the following represent(s) the advantage(s) of the system approach over the r-model approach?

A) Thevenin’s theorem can be used.

B) The effect of changing the load can be determined by a simple equation.

C) There is no need to go back to the ac equivalent model and analyze the entire network.

D) All of the above

Solution:

32. The loaded voltage gain of an amplifier is always more than the no-load level.

A) True

B) False

Solution:

33. The smaller the level of RL, the larger the level of ac voltage gain.

A) True

B) False

Solution:

34. Which of the following is (are) true to achieve a good overall voltage gain for the circuit?

A) The effect of Rs and RL must be considered as a product.

B) The effect of Rs and RL must be considered as a product and evaluated individually.

C) The effect of Rs and RL must be evaluated individually.

D) None of the above

Solution:

35. The _______ the source resistance and/or _______ the load resistance, the less the overall gain of an amplifier.

A) smaller, smaller

B) smaller, larger

C) larger, smaller

D) larger, larger

Solution:

36. The current gain for the Darlington connection is _______.

A) β1 • (β2/2)

B) β1 • β2

C) β1 / β2

D) β1 • (β2 – 1)

Solution:

37. What is the voltage gain of a feedback pair connection?

A) 1

B) –1

C) 100

D) –100

Solution:

38. Which of the following is referred to as the reverse transfer voltage ratio?

A) hi

B) hr

C) hf

D) ho

Solution:

39. In an unbypassed emitter bias configuration hie replaces ______ in the re model.

A) re

B) β

C) βre

D) Ib

Solution:

### Fill-in-the-blanks Questions

1. The _______ of the input signal is one of the first concerns in the sinusoidal ac analysis of transistor networks.

A) period

B) frequency

C) magnitude

D) None of the above

Solution:

2. The _______ model(s) is (are) commonly used in the small-signal ac analysis of transistor networks.

A) re

B) hybrid equivalent

C) re and hybrid equivalent

D) None of the above

Solution:

3. The peak value of the ac input signal is controlled by the _______ in a transistor network for the frequencies in the low to midrange.

A) resistors

B) applied dc voltage

C) capacitors

D) None of the above

Solution:

4. _______ can be applied to determine the response of the ac equivalent circuit.

A) Mesh analysis

B) Node analysis

C) Thevenin’s theorem

D) All of the above

Solution:

5. For transistor amplifiers, the no-load voltage gain is _______ the loaded voltage gain.

A) smaller than

B) greater than

C) the same as

D) None of the above

Solution:

6. The input and output signals are _______ for the typical transistor amplifier at frequencies that permit ignoring the effects of the reactive elements.

A) in phase

B) 180° out of phase

C) either in phase or 180° out of phase

D) None of the above

Solution:

7. One junction of an operating transistor is _______ and the other one is _______.

A) forward-biased, forward-biased

B) forward-biased, reverse-biased

C) reverse-biased, reverse-biased

D) None of the above

Solution:

8. For a common-base configuration, the input impedance is relatively _______ and the output impedance quite _______.

A) high, small

B) small, high

C) small, small

D) high, high

Solution:

9. The output voltage and the input voltage are _______ for the common-base configuration.

A) 45° out of phase

B) 90° out of phase

C) 180° out of phase

D) in phase

Solution:

10. In a common-emitter configuration _______ is the controlling current while _______ is the controlled current.

A) IC, IB

B) IC, IE

C) IB, IC

D) None of the above

Solution:

11. The level of re is determined by ________.

A) α

B) IE

C) β

D) IB

Solution:

12. The output voltage and the input voltage are _______ for the common-emitter configuration.

A) in phase

B) 45° out of phase

C) 90° out of phase

D) 180° out of phase

Solution:

13. The common-emitter configuration has a _______ level of input impedance with a _______ voltage and current gain.

A) moderate, high

B) low, moderate

C) low, low

D) high, low

Solution:

14. ______ refers to the forward transfer current ratio.

A) hi

B) hr

C) hf

D) ho

Solution:

15. For the common-emitter and common-base configurations, the magnitude of ______ and ______ is often not included in the model.

A) hr, ho

B) hi, he

C) hi, hr

D) he, ho

Solution:

16. In a fixed-bias network, the input signal Vi is applied to the _______ of the transistor while the output Vo is off the _______.

A) base, collector

B) base, emitter

C) emitter, collector

D) None of the above

Solution:

17. In a voltage-divider bias configuration, the voltage-divider equation is used to determine the _______.

A) ac level of Vb

B) dc level of IB

C) dc level of VB

D) ac level of Ib

Solution:

18. In a voltage-divider bias configuration, there can be a measurable difference in the results for _______ if the condition ro ≥ 10RC is not satisfied.

A) Zo

B) Av

C) Ai

D) All of the above

Solution:

19. The bypass capacitor in a common-emitter configuration _______ the voltage gain.

A) significantly decreases

B) significantly increases

C) slightly increases

D) slightly decreases

Solution:

20. In an emitter-follower, the voltage gain is _______.

A) slightly less than 1

B) slightly more than 1

C) a very large value

D) None of the above

Solution:

21. In an emitter-follower, the output voltage is _______ with the input voltage.

A) 45° out of phase

B) 90° out of phase

C) 180° out of phase

D) in phase

Solution:

22. An emitter-follower has _______ impedance at the input and _______ impedance at the output.

A) high, high

B) low, high

C) high, low

D) low, low

Solution:

23. _____ is slightly affected if the condition ro ≥ 10RE is not satisfied in the analysis of an emitter-follower configuration.

A) Zi

B) Zo

C) Av

D) Ai

Solution:

24. A common-base configuration has ______ impedance at the input and ______ impedance at the output.

A) high, high

B) high, low

C) low, low

D) low, high

Solution:

25. In a common-base configuration, the input and output voltages are _______ and the output and input currents are _______.

A) 180° out of phase, 180° out of phase

B) 180° out of phase, in phase

C) in phase,180° out of phase

D) in phase, in phase

Solution:

26. Ideally, the changes in the load resistor or the source resistor should have _______ effect on all the parameters of the two-port model.

A) a great

B) a moderate

C) no

D) None of the above

Solution:

27. The loaded voltage gain of an amplifier is _______ the no-load level.

A) always more than

B) always less than

C) always the same as

D) None of the above

Solution:

28. The coupling capacitor places the load and collector resistors in a _______ arrangement.

A) series

B) parallel

C) series-parallel

D) None of the above

Solution:

29. The dc load line and ac load line both have the same _______ .

A) x-intercept

B) y-intercept

C) slope

D) Q-point

Solution:

30. The _______ the level of RL, the ______ the level of ac voltage gain.

A) smaller, higher

B) larger, lower

C) smaller, lower

D) None of the above

Solution:

31. The _______ the source resistance, the ______ the overall gain of an amplifier.

A) larger, higher

B) larger, lower

C) lower, lower

D) None of the above

Solution:

32. The ac voltage gain of a Darlington connection is about _______.

A) 0

B) 1

C) βD

D) None of the above

Solution:

33. The feedback pair uses a(n) _______ transistor driving a(n) _______ transistor, the two devices acting effectively much like one pnp transistor.

A) pnp, npn

B) pnp, pnp

C) npn, npn

D) None of the above

Solution:

34. In an unbypassed emitter-bias configuration _____ replaces re in the hybrid equivalent circuit.

A) hie

B) hfe

C) hre

D) hoe

Solution:

35. In a hybrid equivalent circuit, ______ is determined to make it easier to find the other parameters.

A) Zi

B) Zo

C) Ai

D) Av

Solution:

### Complete List of Chapter Quiz in Electronic Devices and Circuit Theory

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