BJT Amplifier Circuits: Interactive Learning Quizzes for Electronics II

Question 1

In a common-emitter amplifier, what primarily determines the voltage gain?

Accepted Answer

Ratio of collector resistor to emitter resistor

Answer

Emitter resistor

Answer

Collector resistor

Question 2

What is a drawback of using a common-emitter amplifier configuration?

Accepted Answer

Low input impedance

Answer

High voltage gain

Answer

Wide bandwidth

Answer

Current gain

Question 3

The purpose of a small-signal model in BJT amplifier analysis is to:

Accepted Answer

Simplify circuit analysis by considering only small signal variations

Answer

Increase the accuracy of analysis at high frequencies

Answer

Reduce the complexity of circuit design

Answer

Enhance the bandwidth of the amplifier

Question 4

Which factors primarily influence the frequency response of a BJT amplifier?

Accepted Answer

Capacitance of the transistor and load resistance

Answer

Input resistance and biasing current

Answer

Transistor gain and feedback

Answer

Power supply voltage and temperature

Question 5

Which is NOT a potential source of distortion in BJT amplifiers?

Accepted Answer

Linear biasing network

Answer

Nonlinearity of transistor characteristics

Answer

Capacitive coupling between stages

Answer

Thermal effects

Question 6

The primary purpose of the biasing network in a BJT amplifier is to:

Accepted Answer

Establish the quiescent operating point of the transistor

Answer

Increase the gain of the amplifier

Answer

Reduce the bandwidth of the amplifier

Answer

Improve the stability of the amplifier

Question 7

To analyze the frequency response of a BJT amplifier, which graphical technique is commonly employed?

Accepted Answer

Bode plot

Answer

Nyquist plot

Answer

Polar plot

Answer

Smith chart

Question 8

Which technique is used to enhance the linearity of BJT amplifiers?

Accepted Answer

Applying negative feedback

Answer

Operating the transistor in saturation

Answer

Increasing the biasing current

Answer

Decreasing the load resistance

Question 9

To minimize the impact of temperature variations on BJT amplifier performance, which design technique is most effective?

Accepted Answer

Employing a constant-current source

Answer

Increasing the emitter resistance

Answer

Attaching a heat sink

Answer

Using a thermistor

Question 10

The small-signal model of a BJT in the common-emitter configuration consists of which element?

Accepted Answer

Voltage-controlled current source

Answer

Current-controlled voltage source

Answer

Resistor-capacitor network

Question 11

In a common-base amplifier, the input signal is applied to which terminal?

Accepted Answer

Base

Answer

Emitter

Answer

Collector

Question 12

Which statement accurately describes a common-collector amplifier?

Accepted Answer

It acts as a current buffer

Answer

It provides voltage gain

Answer

It has a high output impedance

Question 13

The mid-band voltage gain of a BJT amplifier is determined by which factor(s)?

Accepted Answer

Both emitter and collector resistances

Answer

Emitter resistance

Answer

Collector resistance

Question 14

What is the primary function of a bypass capacitor in a BJT amplifier?

Accepted Answer

Bypass DC current

Answer

Reduce AC gain

Answer

Increase AC gain

Answer

Reduce distortion

Question 15

Which of the following is not a type of BJT amplifier configuration?

Accepted Answer

Common-gate

Answer

Common-emitter

Answer

Common-base

Answer

Common-collector

Question 16

In a common-emitter amplifier, which terminal receives the input signal?

Accepted Answer

Base

Answer

Emitter

Answer

Collector

Answer

Feedback loop

Question 17

Which technique can be used to enhance the stability of a BJT amplifier?

Accepted Answer

Negative feedback

Answer

Positive feedback

Answer

Increasing input capacitance

Answer

Reducing output resistance

Question 18

Which type of amplifier configuration exhibits a high input impedance?

Accepted Answer

Common-collector

Answer

Common-emitter

Answer

Common-base

Answer

Darlington

Question 19

What is the primary function of a bypass capacitor in a BJT amplifier circuit?

Accepted Answer

To pass AC voltage

Answer

To block DC voltage

Answer

To prevent feedback

Answer

To protect the transistor

Question 20

Which factor predominantly determines the voltage gain of a BJT amplifier in the mid-frequency range?

Accepted Answer

Transistor's beta

Answer

Input impedance

Answer

Output impedance

Answer

Feedback factor

Question 21

In a BJT amplifier, the cutoff frequency denotes the maximum frequency at which the amplifier can operate with:

Accepted Answer

-3 dB frequency

Answer

Cutoff frequency

Answer

Resonance frequency

Answer

Passband frequency

Question 22

In a common-emitter BJT amplifier circuit, what is the primary function of the load line, and how does it impact the transistor's operating point?

Accepted Answer

The load line graphically illustrates the relationship between collector current and collector-emitter voltage, determining the quiescent point (Q-point) of the transistor when no signal is applied.

Answer

The load line indicates the maximum possible power output of the amplifier.

Answer

The load line is independent of the specific transistor used in the amplifier.

Answer

The load line is solely relevant for analyzing the amplifier's AC behavior.

Question 23

When biasing a BJT amplifier, which of these is NOT a primary goal?

Accepted Answer

Boosting power output

Answer

Setting the operating point

Answer

Minimizing distortion

Question 24

Which of the following is NOT a valid BJT amplifier configuration?

Accepted Answer

Common-gate

Answer

Common-emitter

Answer

Common-base

Answer

Common-collector

Question 25

In a common-emitter amplifier, the voltage gain is approximately equal to:

Accepted Answer

β

Answer

-β

Answer

α

Answer

1/β

Question 26

The purpose of a biasing resistor in a BJT amplifier is to:

Accepted Answer

Control the current flow

Answer

Reduce noise

Answer

Increase linearity

Answer

Enhance stability

Question 27

Which of the following is a characteristic of a high-frequency amplifier?

Accepted Answer

Wide bandwidth

Answer

Narrow bandwidth

Answer

Low gain

Answer

High gain

Question 28

The gain-bandwidth product of an amplifier:

Accepted Answer

Determines its maximum frequency response

Answer

Is influenced by its feedback

Answer

Limits its input impedance

Answer

Controls its output voltage

Question 29

Which of the following is a type of feedback used in amplifiers to improve stability?

Accepted Answer

Negative feedback

Answer

Positive feedback

Answer

Inductive feedback

Answer

Capacitive feedback

Question 30

A BJT amplifier with a large voltage gain and a small current gain is known as a:

Accepted Answer

Voltage amplifier

Answer

Current amplifier

Answer

Transconductance amplifier

Answer

Transresistance amplifier

Question 31

Which BJT amplifier configuration has the highest input impedance?

Accepted Answer

Common-base

Answer

Common-emitter

Answer

Common-collector

Question 32

In a common-emitter amplifier, the major factor determining the voltage gain is the:

Accepted Answer

Collector resistance

Answer

Emitter resistance

Answer

Base-emitter resistance

Question 33

The simplified equivalent circuit used to analyze BJT amplifiers is called the:

Accepted Answer

Small-signal model

Answer

Large-signal model

Answer

Hybrid model

Question 34

Which factors primarily limit the frequency response of a BJT amplifier?

Accepted Answer

Capacitance and inductance

Answer

Resistance and voltage

Answer

Current and power

Question 35

The load line on a BJT amplifier characteristic curve primarily represents:

Accepted Answer

The range of possible operating points

Answer

The maximum output voltage

Answer

The input impedance

Question 36

In a BJT amplifier circuit, the main purpose of a bypass capacitor is to:

Accepted Answer

Pass DC signals

Answer

Block AC signals

Answer

Increase voltage gain

Question 37

How does negative feedback improve the linearity of a BJT amplifier's output? Illustrate your explanation with an example of a feedback circuit.

Accepted Answer

Negative feedback reduces distortion by counteracting nonlinearities in the amplifier, resulting in a more linear output.

Answer

Negative feedback increases the amplifier's bandwidth by stabilizing the gain.

Answer

Negative feedback enhances the amplifier's stability, making it less susceptible to temperature and component variations.

Answer

Negative feedback reduces noise in the amplifier by decreasing the gain.

Question 38

In a BJT amplifier, which combination of factors primarily determines its bandwidth?

Accepted Answer

Transistor cutoff frequency and circuit capacitances

Answer

Bias conditions only

Answer

Input and load resistance only

Question 39

What is the primary advantage of employing a Darlington pair in a BJT amplifier?

Accepted Answer

Significant increase in both overall gain and input impedance

Answer

Enhanced bandwidth

Answer

Reduced output resistance

Question 40

A characteristic feature of a Class B amplifier is:

Accepted Answer

Conduction angle of less than 180 degrees

Answer

High linearity

Answer

High power consumption

Question 41

In amplifier circuits, the main advantage of a FET over a BJT is:

Accepted Answer

Substantially higher input impedance

Answer

Higher gain

Answer

Lower noise

Question 42

What is the primary function of a bootstrap capacitor in a BJT amplifier?

Accepted Answer

Extends the amplifier's frequency response

Answer

Reduces distortion

Answer

Lowers the input impedance

Answer

Increases the output voltage

Question 43

What is a key advantage of Darlington transistors?

Accepted Answer

Higher power gain

Answer

Lower input impedance

Answer

Improved frequency response

Answer

Reduced distortion

Question 44

The stability factor of a BJT amplifier measures its sensitivity to which factors?

Accepted Answer

Temperature and transistor parameters

Answer

Input signal amplitude and frequency

Answer

Load resistance and supply voltage

Answer

Component tolerances and noise

Question 45

In a BJT amplifier, what is the purpose of a bypass capacitor?

Accepted Answer

To bypass AC signals around the emitter resistor

Answer

To enhance voltage gain

Answer

To block DC signals from reaching the base

Answer

To isolate the base from the emitter

Question 46

What is the main purpose of utilizing a Darlington pair?

Accepted Answer

Substantially increasing current gain

Answer

Improving voltage regulation

Answer

Lowering input impedance

Question 47

Which factor significantly influences the frequency response of a BJT amplifier?

Accepted Answer

Capacitance

Answer

Voltage

Answer

Inductance

Answer

Resistance

Question 48

What is the primary distinction between common-base and common-emitter amplifier configurations?

Accepted Answer

Input impedance and voltage gain

Answer

Current gain

Answer

Phase shift

Answer

Output impedance

Question 49

Which of the following biasing techniques is commonly used to set a BJT amplifier in the active region?

Accepted Answer

Voltage-divider bias

Answer

Collector feedback bias

Answer

Base bias

Answer

Emitter feedback bias

Question 50

What does the Miller effect describe in BJT amplifiers?

Accepted Answer

Increased capacitance due to feedback

Answer

Decrease in voltage gain

Answer

Reduction in output impedance

Answer

Rise in input impedance

Question 51

Differential amplifiers offer which distinct advantage?

Accepted Answer

Improved common-mode rejection ratio

Answer

Lower output impedance

Answer

Enhanced input impedance

Answer

Higher voltage gain

Question 52

What is the critical role of a heat sink in a BJT amplifier?

Accepted Answer

Dissipating heat generated by the transistor

Answer

Reducing output impedance

Answer

Protecting the transistor from over-current

Answer

Increasing input impedance