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ECE Objective Questions { BJT Amplifiers and Transistor }

29.  If two stages of a cascaded amplifier have decibel gains of 60 and 30, then over-all gain is ? dB.

30. All statements regarding complementary to tempole amplifier are correct except
A. it employs two complementary transistors i.e. one NPN and the other PNP type
B. being practically similar to an emitter follower, it produces no voltage gain
C. since their bases are connected together, each transistor is affected in reverse to the other by a given input signal
D. the two collectors are out of phase with each other

31. In amplifiers, the coupling that produces minimum interference with frequency response is
A. direct coupling
B. impeance coupling
C. RC coupling
D. transformer coupling

32.  The most desirable feature of transformer coupling is its
A. higher voltage gain
B. wide frequency range
C. ability to provide impedance matching between stages
D. ability to eliminate hum from the output

33.  In multistage amplifiers, direct coupling is especially suited for amplifying
A. high frequency as signals
B. changes in dc voltages
C. high-level voltages
D. sinusoidal signals

34. Load impedance must match amplifier impedance in order that
A. minimum power is transferred to the load
B. maximum power is transferred to the load
C. efficiency may be held at a high level
D. signal-to-noise ratio is maximized

35.  Parasitic oscillations in amplifiers are caused by
A. negative feedback
B. push-pull operation
C. poor interstage coupling
D. transistor inter-junction capacitance

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