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ECE Objective Questions { BJT Amplifiers and Transistor }



57. A high-Q tuned circuit in an amplifier permits it to have high
A. selectivity
B. fidelity
C. sensitivity
D. frequency range

58. Regarding alpha cut-off frequency fa of a transistor, which of the following statement is not true?
A. it is the frequency at which cc of the transistor drops to 0.707 of its low frequency value cco
B. it is also known as 3-dB frequency
C. it is lower than beta cut-off frequency,
D.it is the frequency at which power gain 11 of the transistor is down by 1/2

59. The relationship between fa and frequencies of a transistor is
A. f?B = K(1 + a) fa
B. fcx = K(1 ? cc) fp
C. fp = K(1 ? cc) / fa
D. = K(1 ? a) fu

60. The gain-bandwidth product transistor is given by
A. fT = 130/fp
B. fT =130/fa
C. fT = x
D.fT=I3Oxf

61. A transistor has gain-bandwidth product of 1000 MHz and 130 = 100. The approximate value of its f MHz.
A.1000
B.10
C.104
D.100

62. A transistor has gain-bandwidth product of 1000 MHz and 130 = 100. The approximate value of fp is ___ MHz
A.800
B.(g) 10
C.500
D. none of the above

63. The biggest disadvantage of directcou pled & amplifiers is that
A. they cannot amplify ac voltage
B. they do not use capacitors between different stages
C. Hartley
D. Armstrong

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