1. For the circuit shown below express v0 as a function of v1 and v2.
Correct : B. v0 = v2 – v1
2. Determine Ad and Ac for the given circuit.
Correct : A. ac = 0 and ad = 1
3. Determine the voltage gain for the given circuit known that R1 = R3 = 10kΩ abd R2 = R4 = 100kΩ.
Correct : B. 10
4. What is trans-conductance?
Correct : B. ratio of change in drain current to change in gate to source voltage
5. What is the value of trans conductance?
Correct : C. 0.1
6. 002. What is the value ofgm?
Correct : C. 0.002
7. Find the maximum value of gm for FET with IDSS=10mA, Vp=-2V, VGS=5V?
Correct : A. 10ms
8. A FET has IDSS=4ID and gm0 = 10mS then gm =
Correct : C. 5ms
9. Determine the value of output impedance for JFET, if the value of gm =1mS?
Correct : A. 1kohm
10. In a small signal equivalent model of an FET, What does gm VGS stand for?
Correct : B. voltage controlled current source
11. Given yfs = 3.6mS and yos = 0.02mS, determine r0?
Correct : C. 50kohm
12. Which of the following statement is incorrect?
Correct : C. cb amplifier is a voltage buffer
13. Given hfe = 60, hie=1000Ω, hoe = 20μ Ω–, hre = 2 * 10-4. Find the current gain of the BJT, correct up to two decimal points.
Correct : A. – 58.44
14. Consider the circuit. Given hfe = 50, hie = 1200Ω. Find voltage gain.
Correct : A. – 278
15. Given that IB = 5mA and hfe = 55, find load current.
Correct : B. 280ma
16. Consider the following circuit, where source current = 10mA, hfe = 50, hie = 1100Ω, then for the transistor circuit, find output resistance RO and input resistance RI.
Correct : C. ro = ∞, ri = 21Ω
17. For the given circuit, input resistance RI = 20Ω, hfe = 50. Output resistance = ∞. Find the new values of input and output resistance, if a base resistance of 2kΩ is added to the circuit.
Correct : C. ri = 59Ω, ro = ∞
18. If source resistance in an amplifier circuit is zero, then voltage gain (output to input voltage ratio) and source voltage gain (output to source voltage ratio) are the same.
Correct : A. true
19. The Differential output of the difference amplifier is the amplification of
Correct : A. difference between the voltages of input signals
20. The inputs to the differential amplifier are applied at
Correct : B. at the gates of m1 and m2
21. In Common Mode Differential Amplifier, the outputs Vout1 and Vout2 are related as:
Correct : D. vout1 and vout2 have same amplitude and are in phase with each other but out of phase with their respective inputs
22. In a small signal differential gain vs input CM level graph, the gain decreases after V2 due to:
Correct : C. when common mode voltage is greater than or equal to v2, the input transistors enter triode region, the gain begins to fall
23. Consider a voltage amplifier having a frequency response of the low-pass STC type with a dc gain of 60 dB and a 3-dB frequency of 1000 Hz. Then the gain db at
Correct : D. f = 1mhz is 0 db
24. STC networks can be classified into two categories: low-pass (LP) and high-pass (HP). Then which of the following is true?
Correct : B. lp network passes dc and low frequencies and attenuate high frequency and opposite for hp network
25. The signal whose waveform is not effected by a linear circuit is
Correct : C. sine/cosine wave signal
26. Which of the following is not a classification of amplifiers on the basis of their frequency response?
Correct : D. none of the mentioned
27. General representation of the frequency response curve is called
Correct : A. bode plot
28. Under what condition can the circuit shown be called a compensated attenuator.
Correct : A. c1r1 = c2r2
29. Which of the following is true?
Correct : D. none of the mentioned
30. Which of the following is true?
Correct : D. all of the mentioned
31. During high frequency applications of a B.J.T., which parasitic capacitors arise between the base and the emitter?
Correct : A. cje and cb
32. During high frequency applications of a B.J.T., which parasitic capacitors arise between the collector and the emitter?
Correct : A. no capacitor arises
33. During high frequency applications of a B.J.T, which parasitic capacitors arise between the collector and the base?
Correct : D. cµ
34. 3 BJT FREQUENCY RESPONSE
Correct : B. ccs and cµ
35. Which parasitic capacitors do not affect the frequency response of the C.E. stage, of the B.J.T.?
Correct : D. no parasitic capacitor gets deactivated
36. Which parasitic capacitors don’t affect the frequency response of the C.B. stage of the B.J.T.?
Correct : B. all the parasitic capacitances
37. Which parasitic capacitors don’t affect the frequency response of the C.C. stage of the B.J.T.?
Correct : A. ccs
38. If the transconductance of the B.J.T increases, the transit frequency
Correct : A. increases
39. If the total capacitance between the base and the emitter increases by a factor of 2, the transit frequency
Correct : A. reduces by 2
40. Which effect plays a critical role in producing changes in the frequency response of the B.J.T.?
Correct : A. thevenin’s effect
41. If a C.E. stage has a load Rl and transconductance gm, what is the factor by which the capacitance between the base and the collector at the input side gets multiplied?
Correct : A. 1 + gmrl
42. If a C.E. stage has a load Rl and transconductance gm, what is the factor by which the capacitance between the base and the collector at the output side gets multiplied?
Correct : A. 1 + 1/gmrl
43. Given that transition capacitance is 5 pico F and diffusion capacitance is 80 pico F, and base emitter dynamic resistance is 1500 Ω, find the β cut-off frequency.
Correct : A. 7.8 x 106 rad/s
44. 8 x 106.
Correct : C. 141.42
45. Gain bandwidth frequency is GBP= 3000 Mhz. The cut-off frequency is f=10Mhz. What is the CE short circuit current gain at the β cutoff frequency?
Correct : A. 212
46. Which of the statement is incorrect?
Correct : A. at unity gain frequency the ce short circuit current gain becomes 1
47. In an RC coupled CE amplifier, when the input frequency increases, which of these are incorrect?
Correct : B. voltage gain increases
48. In Miller’s theorem, what is the constant K?
Correct : B. internal voltage gain
49. When applying miller’s theorem to resistors, resistance R1 is for node 1 and R2 for node 2. If R1>R2, then for same circuit, then for capacitance for which the theorem is applied, which will be larger, C1 or C2?
Correct : A. c1
50. Find net voltage gain, given hfe = 50 and hie = 1kΩ.
Correct : D. -27.68
51. Given that capacitance w.r.t the input node is 2pF and output node is 4pF, find capacitance between input and output node.
Correct : A. 0.67 pf
52. Consider an RC coupled amplifier at low frequency. Internal voltage gain is -120. Find the voltage gain magnitude, when given that collector resistance = 1kΩ, load = 9kΩ, collector capacitance is 0. is 0.1μF, and input frequency is 20Hz.
Correct : C. 15
53. 15Hz
Correct : B. 612 hz
54. Find the 3-dB frequency given that the gain of RC coupled amplifier is 150, the low frequency voltage gain is 100 and the input frequency is 50Hz.
Correct : B. 55.9 hz
55. What is the phase shift in RC coupled CE amplifier at lower 3dB frequency?
Correct : B. 225°
56. We cannot use h-parameter model in high frequency analysis because
Correct : B. junction capacitances are not included in it
57. Which of the statement is incorrect?
Correct : A. at unity gain frequency the ce short circuit current gain becomes 1
58. The collector current will not reach the steady state value instantaneously because of
Correct : A. stray capacitances
59. For the BJT, β=∞, VBEon=0.7V VCEsat=0.7V. The switch is initially closed. At t=0, it is opened. At which time the BJT leaves the active region?
Correct : B. 50ms
60. The technique used to quickly switch off a transistor is by
Correct : C. reverse biasing its base to emitter junction
61. Which of the following circuits helps in the applications of switching times?
Correct : B. d)
62. Which of the following helps in reducing the switching time of a transistor?
Correct : A. a resistor connected from base to ground
63. The time taken for a transistor to turn from saturation to cut off is
Correct : B. directly proportional to charge carriers
64. Switching speed of P+ junction depends on
Correct : D. life time of minority carriers in n junction
65. Fixed voltage regulators and adjustable regulators are often called as
Correct : A. series dissipative regulators
66. Linear series regulators are suited for application with
Correct : B. medium current
67. A series switching regulators
Correct : A. improves the efficiency of regulators
68. The switching regulators can operate in
Correct : D. all the mentioned
69. It may be required to store energy for a specified amount of time during power failure especially if the system is designed for a computer power supply.
Correct : B. 1,2,3 and 4
70. Which among the following act as a switch in switching regulator?
Correct : C. transistors
71. What should be the frequency range of pulse generator?
Correct : D. 20 khz
72. Filter used in switching regulator’s are also as called
Correct : C. dc transformer
73. Which of the following is considered to be the most important components of the switching regulator?
Correct : B. rl or rlc filter
74. Which is the most commonly used low voltage switching regulators?
Correct : C. silicon steel ei butt stacks
75. The diode in a half wave rectifier has a forward resistance RF. The voltage is Vmsinωt and the load resistance is RL. The DC current is given by
Correct : B. vm/(rf+rl)π
76. What is the output as a function of the input voltage (for positive values) for the given figure. Assume it’s an ideal op-amp with zero forward drop (Di=0)
Correct : C. vi
77. In a half wave rectifier, the sine wave input is 50sin50t. If the load resistance is of 1K, then average DC power output will be?
Correct : B. 2.5v
78. Efficiency of a half wave rectifier is
Correct : C. 40.6%
79. If peak voltage for a half wave rectifier circuit is 5V and diode cut in voltage is 0.7, then peak inverse voltage on diode will be?
Correct : C. 4.3v
80. Transformer utilisation factor of a half wave rectifier is
Correct : C. 0.287
81. If the input frequency of a half wave rectifier is 100Hz, then the ripple frequency will be
Correct : C. 100hz
82. Efficiency of a centre tapped full wave rectifier is
Correct : D. 81.2%
83. A full wave rectifier delivers 50W to a load of 200Ω. If the ripple factor is 2%, calculate the AC ripple across the load.
Correct : A. 2v
84. In a centre tapped full wave rectifier, RL=1KΩ and for diode Rf=10Ω. The primary voltage is 800sinωt with transformer turns ratio=2. The ripple factor will be
Correct : B. 48%
85. Due to centre tap Vm=400/2=200) IRMS=198/√2=140mA, IAVG=2*198/ π=126mA. ϒ=[(140/126)2-1]1/2=0.48. So, ϒ=48%.
Correct : C. 0.693
86. If the peak voltage on a centre tapped full wave rectifier circuit is 5V and diode cut in voltage is 0.7. The peak inverse voltage on diode is
Correct : B. 9.3v
87. What is done in switching regulators to minimize its power dissipation during switching?
Correct : C. uses external transistor and 1mh choke
88. 33/ Ipk
Correct : B. 1- i , 2- ii , 3- iii
89. Choose the correct statement
Correct : C. mosfet is a unipolar, voltage controlled, three terminal device
90. The arrow on the symbol of MOSFET indicates
Correct : B. the direction of electrons
91. The controlling parameter in MOSFET is
Correct : B. ig
92. In the internal structure of a MOSFET, a parasitic BJT exists between the
Correct : B. source & drain terminals
93. In the transfer characteristics of a MOSFET, the threshold voltage is the measure of the
Correct : A. minimum voltage to induce a n-channel/p- channel for conduction
94. The output characteristics of a MOSFET, is a plot of
Correct : B. id as a function of vds with vgs as a parameter
95. SMPS is used for
Correct : B. obtaining controlled dc power supply
96. Choose the incorrect statement.
Correct : C. smps has low input ripple
97. is used for critical loads where temporary power failure can cause a great deal of inconvenience.
Correct : B. ups
98. is used in the rotating type UPS system to supply the mains.
Correct : C. alternator
99. Static UPS requires
Correct : C. both inverter and rectifier
100. Usually batteries are used in the UPS systems.