Test: Large Signal Amplifiers


10 Questions MCQ Test Topicwise Question Bank for Electronics Engineering | Test: Large Signal Amplifiers


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Attempt Test: Large Signal Amplifiers | 10 questions in 30 minutes | Mock test for Electronics and Communication Engineering (ECE) preparation | Free important questions MCQ to study Topicwise Question Bank for Electronics Engineering for Electronics and Communication Engineering (ECE) Exam | Download free PDF with solutions
QUESTION: 1

Assertion (A): The harmonic distortion of an amplifier increases at higher power levels,
Reason (R): For high quality audio amplifiers, the maximum THD is 0.7% at the desired listening level.

Solution:
QUESTION: 2

A common-emitter amplifier, with a self-bias circuit to bias the transistor in the active mode, -is an example of a class ____ amplifier.

Solution:

The O-point of class-A amplifier is located in active region i.e. at the mid-point of dc load line as shown below.

QUESTION: 3

The advantages of class B as compared with class A operation are
1. efficiency is higher.
2. possible to obtain greater power output.
3. less distortion and noise interference.
4. negligible power loss at no input signal. Of these the statements:

Solution:

Compared to class A operation, class B operation has

  • higher efficiency (r| = 78.5%)
  • greater output power 
  • more distortion and noise interference.
  • negligible power loss at no input signal i.e. no power drain since transistor in class B operation will not consume any power if signal is not applied.

Hence, statements 1,2 and 4 are correct.

QUESTION: 4

Assertion (A): In a system where the power supply is limited, such as those operating from solar cells or a battery, the output power is usually delivered through a push-pull class B transistor circuit.

Reason (R): It is possible to obtain greater power output, higher efficiency and negligible power loss at no signal with the help of a push- pull class B transistor circuit.

Solution:
QUESTION: 5

For a given transistor, the thermal resistance is 8 °C/W and the ambient temperature TA is 27°C. if the transistor dissipates 3 W of power, the junction temperature Tj will be

Solution:

We know that,

or

QUESTION: 6

Crossover distortion refers to the distortion caused due to

Solution:
QUESTION: 7

In a class B amplifier, VCE(min) = 2 V and supply voltage Vcc = 15 V. The collector circuit efficiency is approximately

Solution:

Collector circuit efficiency is 

QUESTION: 8

The maximum theoretical efficiency of a class A amplifier can be

Solution:
QUESTION: 9

For a transistor, Tj = 160°C, TA = 40°C and θJ-A = 80°C/W. What is the power that the transistor can safely dissipate in free air?

Solution:

The power dissipated by the transistor is

QUESTION: 10

ln a class A amplifier, VCE(max) = 15 VCE(min) = 1 V. The overall efficiency for series fed load and transformer coupled load are respectively

Solution:

For series-fed load, overall efficiency,

For transformer-coupled load, overall efficiency,

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