Q.1
Which of the power amplifiers has the lowest overall efficiency?
  • Class A
  • Class B or AB
  • Class C
  • Class D
Q.2
By how much does the output signal vary for a class AB power amplifier?
  • 360º
  • 180º
  • Between 180º and 360º
  • Less than 180º
Q.3
How many transistors must be used in a class B power amplifier to obtain the output for the full cycle of the signal?
  • 0
  • 1
  • 2
  • 3
Q.4
Which type of power amplifier is biased for operation at less thanof the cycle?
  • Class A
  • Class B or AB
  • Class C
  • Class D
Q.5
Quiescent power is the power dissipation of a transistor
  • with no signal input.
  • with no load.
  • under full load.
  • along the dc load line.
Q.6
What is the maximum temperature rating for silicon power transistors?
  • 50º to 80º
  • 100º to 110º
  • 150º to 200º
  • 250º to 300º
Q.7
What is the maximum efficiency of a class B circuit?
  • 90%
  • 78.5%
  • 50%
  • 25%
Q.8
A class C amplifier has a tank circuit in the output. The amplifier is conducting only 28°. The output voltage is
  • 0 V.
  • a dc value equal to VC
  • a sine wave.
  • a square wave with a frequency determined by the tank.
Q.9
NMOS and pMOS transistors can be used for class B.
  • True
  • False
Q.10
The class ________ amplifier is biased below cutoff.
  • A
  • AB
  • B
  • C
Q.11
A class ________ amplifier is biased slightly above cutoff and operates in the linear region for slightly more thanof the input cycle.
  • A
  • B
  • C
  • AB
Q.12
The maximum efficiency of a transformer-coupled class A amplifier is ________.
  • 25%
  • 50%
  • 78.5%
  • 63.6%
Q.13
The maximum efficiency of a class B amplifier is ________ percent.
  • 50
  • 25
  • 70
  • 79
Q.14
Which of the following is (are) the disadvantage(s) of a class B complementary-symmetry circuit?
  • It needs two separate voltage sources.
  • There is crossover distortion in the output signal.
  • It does not provide exact switching of one transistor off and the other on at the zero-voltage condition.
  • All of the above
Q.15
In practice, the efficiency of a capacitively coupled class A amplifier is about ________%.
  • 25
  • 40
  • 70
  • 10
Q.16
Which of the following transistors has been quite popular as the driver device for class D amplification?
  • BJT
  • FET
  • UJT
  • MOSFET
Q.17
The least efficient amplifier among all classes is
  • class
  • class
  • class A
  • class
Q.18
In a class AB amplifier, if the VBE drops are not matched to the diode drops or if the diodes are not in thermal equilibrium with the transistors, this can result in
  • a current mirror.
  • diode separation.
  • crossover distortion.
  • thermal runaway.
Q.19
Which operation class is generally used in radio or communications?
  • A
  • B
  • AB
  • C
  • E. D
Q.20
Calculate the efficiency of a transformer-coupled class A amplifier for a supply ofV and an output of V(p) =V.
  • 25%
  • 33.3%
  • 50%
  • 78.5%
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