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ECE Objective Questions { BJT Amplifiers and Transistor }

36.  A buffer amplifier is used for coupling purposes in RF amplifiers because it provides
A. maximum loading and minimum mismatch
B. minimum loading and minimum mismatch
C. maximum loading and maximum mismatch
D. minimum loading and maximum mismatch

37. A class-C amplifier is used as a
A. dc amplifier
B. differential amplifier
C. audio amplifier
D. RF carrier amplifier

38. A dc amplifier amplifiers
A. dc only
B. both dc and ac
C. ac only
D. only signals of frequencies laying between 20 Hz and 20 kHz

39. Which of the following class of amplifiers has the highest amount of distortion?
A. class-A
B. class-B
C. class-AB
D. class-C

40. A large sacrifice factor in a negative feed-book amplifier leads to
A. inferior performance
B. increased output impedance
C. characteristics impossible to achieve without feedback
D. precise control over output

41. Negative feedback in an amplifier
A. lowers its lower 3-dB frequency
B. raises its upper 3-dB frequency
C. increases it bandwidth
D. all of the above

42. Negative feedback reduces distortion in an amplifier only when it
A. comes as part of input signal
B. is part of its output
C. is generated within it
D. exceeds a certain safe level

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