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ECE : Analog Electronics - Quiz(MCQ)
1 .
The abbreviation PIV in the case of a diode stands for ______
A)
Peak Inverse Voltage
B)
Peak Inferior Voltage
C)
Peak Internal Voltage
D)
Problematic Inverse Voltage

Correct Answer :   Peak Inverse Voltage

Explanation : PIV stands for Peak Inverse Voltage. It is the maximum reverse bias voltage which a diode can bear without breakdown.

2 .
What is meant by the PIV rating of a diode?
A)
Maximum power allowable to a diode
B)
Minimum potential required by a diode to reach conduction state
C)
Maximum reverse bias potential which can be applied across a diode without breakdown
D)
Maximum forward bias potential which can be applied across a diode without breakdown

Correct Answer :   Maximum reverse bias potential which can be applied across a diode without breakdown

Explanation : PIV rating indicates the maximum allowable reverse bias voltage which can be safely applied to a diode. If a reverse potential is greater than PIV rating then the diode will enter reverse breakdown region.

3 .
Which of the following oscillators is suitable for frequencies in the range of mega hertz?
A)
Wien bridge
B)
Hartley
C)
RC phase shift
D)
Both (A) and (C)

Correct Answer :   Hartley

Explanation : Only LC oscillators are suitable for MHz range.

4 .
To prevent a DC return between source and load, it is necessary to use
A)
resistor between source and load
B)
inductor between source and load
C)
Both (A) and (B)
D)
capacitor between source and load

Correct Answer :   capacitor between source and load

5 .
The action of JFET in its equivalent circuit can best be represented as a
A)
Current controlled Current source
B)
Current controlled voltage source
C)
Voltage controlled current source
D)
Voltage controlled voltage source

Correct Answer :   Voltage controlled current source

6 .
In a CB amplifier the maximum efficiency could be
A)
25%
B)
50%
C)
75%
D)
99%

Correct Answer :   25%

7 .
In a p+n junction diode under reverse bias, the magnitude of electric field is maximum at
A)
The edge of the depletion region on the p-side
B)
The p+n junction
C)
The edge of the depletion region on the n-side
D)
The center of the depletion region on the n-side

Correct Answer :   The p+n junction

8 .
The diode current equation is not applicable in _______.
A)
Unbiased state
B)
Reverse biased state
C)
Forward biased state
D)
It is applicable in all bias states

Correct Answer :   It is applicable in all bias states

Explanation : Diode equation is I=IO(eqV/kT – 1). It is applicable in all bias condition that is forward, reverse and unbiased states.

9 .
What is the value of the voltage equivalent of temperature at room temperature (27oC)?
A)
0.26mV
B)
26mV
C)
36mV
D)
260mV

Correct Answer :   26mV

Explanation : Voltage equivalent of temperature VT is equal to the product of Boltzman constant (J.K-1) and temperature in Kelvin. At a temperature of 27°C, it’s value is VT=KT/q=26mV.

10 .
What happens to cut-in voltage when the temperature increases?
A)
Cut-in voltage decreases
B)
Cut-in voltage increases
C)
Cut-in voltage either increases or decreases
D)
Cut-in voltage doesn’t depend on temperature

Correct Answer :   Cut-in voltage decreases

Explanation : As temperature increases the conductivity of a semiconductor increases. The diode conducts smaller voltage at larger temperature. Therefore, cut-in voltage decreases.

11 .
When temperature increases, reverse saturation current _______
A)
Increases
B)
Decreases
C)
Doesn’t depend on temperature
D)
Either increases or decreases

Correct Answer :   Increases

Explanation : As temperature increases the conductivity of a semiconductor increases. Reverse saturation current increases as temperature increases.

12 .
For a base current of 10 μA, what is the value of collector current in common emitter if βdc = 100
A)
100 μA
B)
10 μA
C)
10 mA
D)
1 mA

Correct Answer :   1 mA

Explaination :

IC = 10 x 100 μA = 1 mA.

13 .
An RC coupled amplifier has an open loop gain of 200 and a lower cutoff frequency of 50 Hz. If negative feedback with β = 0.1 is used, the lower cut off frequency will be
A)
about 2.38 Hz
B)
about 5 Hz
C)
about 50 Hz
D)
about 70.5 Hz

Correct Answer :   about 2.38 Hz

Explaination : New lower cutoff frequency 50 / 1+200x0.1

14 .
The load impedance ZL of a CE amplifier has R and L in series. The phase difference between output and input will be
A)
B)
180°
C)
more than 90° but less than 180°
D)
more than 180° but less than 270°

Correct Answer :   more than 180° but less than 270°

Explaination : It is 180° for purely resistive load and between 180° and 270° for R-L load.

15 .
A constant current signal across a parallel RLC circuits gives an output of 1.4v at the signal frequency of 3.89KHZ and 4.1KHZ. At the frequency of 4KHZ, the output voltage will be
A)
1 v
B)
2 v
C)
1.4 v
D)
2.8 v

Correct Answer :   2 v

16 .
Which of the following is not associated with a p-n junction
A)
Depletion capacitance
B)
Junction capacitance
C)
Channel length modulation
D)
Charge storage capacitance

Correct Answer :   Channel length modulation

17 .
The cascade amplifier is a multistage configuration of
A)
CB-CC
B)
CE-CB
C)
CC-CB
D)
CE-CC

Correct Answer :   CE-CB

18 .
An npn BJT has gm = 38 mA/v, Cµ = 10-14 F, Cπ = 4 × 10-13 F and DC current gain β0 = 90. For this transistor fT & fβ are
A)
B)
C)
D)

Correct Answer :   fT = 1.47 x 1010 Hz & fβ = 1.64 x 108 Hz

19 .
Negative feedback in an amplifier
A)
Increases noise
B)
Reduces bandwidth
C)
Increase frequency &phase distortion
D)
Reduces gain

Correct Answer :   Reduces gain

20 .
Calculate the reverse saturation current of a diode if the current at 0.2V forward bias is 0.1mA at a temperature of 25°C and the ideality factor is 1.5.
A)
5.5x 10-10 A
B)
5.5x 10-9 A
C)
5.5x 10-7 A
D)
5.5x 10-8 A

Correct Answer :   5.5x 10-7 A

Explaination : I=I0×(e(V/ηVT) – 1) where I0 = reverse saturation current
η = ideality factor
VT = thermal voltage
V = applied voltage
Here, I = 0.1mA, η = 1.5, V = 0.2V, VT = TK/11600
Therefore, VT at T = 25+273=298 is 298/11600 = 0.0256V.
Therefore, reverse saturation currentReverse saturation current calculation
IO=0.00055mA = 5.5×10-7A.

21 .
Find the applied voltage on a forward biased diode if the current is 1mA and reverse saturation current is 10-10. Temperature is 25°C and takes ideality factor as 1.5.
A)
0.526V
B)
0.618V
C)
0.658V
D)
0.726V

Correct Answer :   0.618V

Explaination : I=I0×(e(V/ηVT)-1) where I0 = reverse saturation current
η = ideality factor
VT = thermal voltage
V = applied voltage
VT at T = 25+273=298 is 298/11600 = 0.0256V, η = 1.5, I = 1mA, I0 = 10-10A
Applied voltage equation with calculation

22 .
If current of a diode changes from 1mA to 10mA what will be the change in voltage across the diode. The ideality factor of diode is 1.2.
A)
7.18V
B)
0.718V
C)
0.0718V
D)
0.00728V

Correct Answer :   0.0718V

Explaination : η = 1.2, I2 = 10mA, I1 = 1mA and take VT = 0.026V

23 .
What is quiescent point or Q-point?
A)
The point of V-I graph where slope is 0.5
B)
The point at which current equal to voltage
C)
Operating point of device
D)
The point at which device have maximum functionality

Correct Answer :   Operating point of device

Explanation : Quiescent point of a device represents operating point of a device. For a diode quiescent point is determined by constant DC current through the diode. The Q-point is the DC voltage or current at a specified terminal of an active device with no input applied. A bias circuit is used to supply this steady voltage/current.

24 .
The reciprocal of slope of current-voltage curve at Q-point gives ___________
A)
AC resistance
B)
Nominal resistance
C)
Minimum impedance
D)
Maximum dynamic resistance

Correct Answer :   AC resistance

Explanation : Reciprocal of slope of I-V graph at q-point gives AC or dynamic resistance. The inverse of slope will be change in voltage by change in current which is known as dynamic resistance.

25 .
As the slope of I-V graph at the Q point increases, AC resistance will ______
A)
Increase
B)
Decrease
C)
Either increase or decrease
D)
None of the above

Correct Answer :   Decrease

Explanation : Slope of I-V graph at q-point is reciprocal of dynamic or AC resistance. Therefore, as slope increases resistance decreases.

26 .
Average AC resistance and dynamic resistance are _______
A)
Always Equal
B)
Never equal
C)
Both represents same quantity
D)
Calculated from V-I graph

Correct Answer :   Calculated from V-I graph

Explanation : Average AC resistance and dynamic or AC resistance are not exactly the same. They both measure the resistance in different ways. AC resistance is slope of the tangent of the curve of characteristic graph at Q-point. But average AC resistance is measured by measuring the slope of straight line between the limits of operation.

27 .
After cut-in voltage AC resistance of diode _________
A)
Slightly decreases
B)
Slightly increases
C)
Decreases exponentially
D)
Increases exponentially

Correct Answer :   Decreases exponentially

Explanation : After cut-in voltage current exponentially increases with small increase in voltage. This will considerably reduce resistance.

28 .
DC resistance of diode is measured at _________
A)
Q-point
B)
Knee current
C)
Cut-in voltage
D)
Reverse breakdown point

Correct Answer :   Q-point

Explanation : Static or DC resistance of a diode is the resistance offered by a diode at its q-point. DC resistance represents steady state. That is, it is calculated by treating current and voltage as constants.

29 .
For a diode, at 10mA DC resistance is 70Ω. The voltage corresponding to 10mA will be ________
A)
0.5V
B)
0.6V
C)
0.7V
D)
0.8V

Correct Answer :   0.7V

Explanation : Static or DC resistance is the resistance of a diode at its operating point.
Resistance = voltage/current
Therefore, voltage = current x resistance = 10mA x 70 = 0.7V

30 .
In a BJT circuit a pnp transistor is replaced by npn transistor. To analyse the new circuit
A)
replace all calculated voltages by reverse values
B)
all calculations done earlier have to be repeated
C)
replace all calculated currents by reverse values
D)
replace all calculated voltages and currents by reverse values

Correct Answer :   replace all calculated voltages and currents by reverse values

Explanation : All voltages and currents have reverse polarity.

31 .
To protect the diodes in a rectifier and capacitor input filter circuit it is necessary to use
A)
surge inductor
B)
surge resistor
C)
surge capacitor
D)
None of the above

Correct Answer :   surge resistor

32 .
In a circuit of figure, Vs = 10 cos(ωt) power drawn by the 2Ω resistor is 4 watts. The power factor is
A)
0.3
B)
0.4
C)
0.6
D)
None of the above

Correct Answer :   0.6

Explaination : Analog Electronics

33 .
The quiescent collector current IC, and collector to emitter voltage VCE in a CE connection are the values when
A)
ac signal is zero
B)
ac signal is low
C)
ac signal is negative
D)
Either (A) or (B)

Correct Answer :   ac signal is zero

Explaination : Quiescent-operation means operation when ac signal is not applied.

34 .
Figure shows the self bias circuit for CE amplifier and its equivalent circuit. VBB and RB respectively are
A)
2 V and 4 k ohm
B)
2 V and 10 k ohm
C)
5 V and 4 k ohm
D)
10 V and 4 k ohm

Correct Answer :   2 V and 4 k ohm

Explaination :

35 .
The open loop gain of an amplifier is 200. If negative feedback with β = 0.2 is used, the closed loop gain will be
A)
2.2
B)
4.878
C)
40.12
D)
200

Correct Answer :   4.878

Explanation : Closed loop gain = 200 / 1+0.2x200

36 .
An RC oscillator uses
A)
one RC combination
B)
two RC combinations
C)
at least three RC combinations
D)
Either (A) or (B)

Correct Answer :   at least three RC combinations

Explanation : One RC combination can give a phase shift of less them 90°. Therefore 3 RC combinations are required for 180° phase shift.

37 .
The main advantage of CMOS circuit is
A)
high gain
B)
high output impedance
C)
low power consumption
D)
high gain and high output impedance

Correct Answer :   low power consumption

Explanation : Low power consumption is a big advantage in digital circuits.

38 .
Ac signals are given to both inverting and non-inverting terminals of an op-amp. When will the output maximum
A)
when the phase difference between the inputs is 0 or 180°
B)
when the phase difference between the inputs is 180°
C)
when the phase difference between the inputs in 90°
D)
when the phase difference between the inputs is 0°

Correct Answer :   when the phase difference between the inputs is 180°

Explanation : For non-inverting terminal input, output is in phase with input. For inverting terminal input, output is 180° out of phase with input. If inputs have 180° phase difference, outputs will be in phase and additive.

39 .
In a bridge rectifier circuit the rms value of input ac voltage is 10 V. The PIV across each diode is
A)
7.07 V
B)
10 V
C)
28.28 V
D)
14.14 V

Correct Answer :   14.14 V

Explanation :

PIV is √2 x 10 = 14.14 V.

40 .
A transistor with a = 0.9 and ICBO = 10 μA is biased so that IBQ = 90 μA. Then IEQ will be
A)
5 mA
B)
5.2 mA
C)
5.15 mA
D)
990 mA

Correct Answer :   990 mA

Explaination :

IEQ = ICQ + IBQ = 910 μA + 90 μA => 990 μA.

41 .
A difference amplifier using op-amp has closed loop gain = 50. If input is 2 V to each of inverting and non-inverting terminals, output is 5 mA. Then CMRR =
A)
20
B)
200
C)
2000
D)
20000

Correct Answer :   20000

Explaination :

42 .
The coupling capacitor in amplifier circuits
A)
affects dc biasing
B)
does not affect dc biasing
C)
affects dc biasing to some extent
D)
Both (B) and (C)

Correct Answer :   does not affect dc biasing

43 .
The most commonly used amplifier in sample & hold circuits is
A)
A unity gain inverting amplifier
B)
A unity gain non-inverting amplifier
C)
An inverting amplifier with a gain of 10
D)
An inverting amplifiers with a gain of 100

Correct Answer :   A unity gain inverting amplifier

44 .
An n-channel JFET has IDSS = 2mA and VP = -4 v. Its transconductance gm = in (mA/V) for an applied gate to source voltage VGS = -2 v is
A)
0.25
B)
0.5
C)
0.75
D)
1

Correct Answer :   0.5

45 .
In a common emitter, unbypassed resister provides
A)
current series feedback
B)
voltage shunt feedback
C)
negative voltage feedback
D)
positive current feedback

Correct Answer :   negative voltage feedback

46 .
The current gain of a bipolar transistor drops at high frequencies because of
A)
The early effect
B)
Parasitic inductive elements
C)
Transistor capacitances
D)
High current effects in the base

Correct Answer :   Transistor capacitances

47 .
In ideal diode model diode in forward bias is considered as a ________
A)
Resistor
B)
Capacitor
C)
Perfect insulator
D)
Perfect conductor

Correct Answer :   Perfect conductor

Explanation : In ideal diode model the diode is considered as a perfect conductor in forward bias and perfect insulator in reverse bias. That is voltage drop at forward bias is zero and current through the diode at reverse bias is zero.

48 .
An amplifier using an opamp with slew rate SR=1v/µsec has a gain of 40db.if this amplifier has to faithfully amplify sinusoidal signals from dc to 20 KHz without introducing any slew-rate induced distortion, then the input signal level must not exceed
A)
79.5 mV
B)
39.5mV
C)
395mV
D)
795mV

Correct Answer :   79.5 mV

49 .
A full wave rectifier circuit using centre tapped transformer and a bridge rectifier are fed at 100 V, 50 Hz. The frequencies of outputs in these two rectifiers are
A)
50 Hz each
B)
100 Hz each
C)
50 Hz and 100 Hz
D)
100 Hz and 50 Hz

Correct Answer :   100 Hz each

Explaination : Output wave in each case has two cycles for one cycle of input wave.

50 .
When the ac base voltage in a CE amplifier circuit is too high, the ac emitter current is
A)
distorted
B)
constant
C)
alternating
D)
zero

Correct Answer :   distorted

Explanation : A high signal causes distortion because v-i characteristics of BJT is non-linear.

51 .
The gain of an FET amplifier can be changed by changing
A)
rm
B)
gm
C)
Rd
D)
None of the above

Correct Answer :   gm

Explaination : Gain is proportional to gm .

52 .
A power transistor dissipates 5 W. If ambient temperature is 30° and case to air thermal resistance is 10° C/W, the case temperature is
A)
20°C
B)
32°C
C)
80°C
D)
305°C

Correct Answer :   80°C

Explaination :

53 .
Voltage Series (feedback also called series-shunt feedback) results in
A)
Increase in both input & output impedances
B)
Increase in input impedance & decreases in output impedance
C)
Decreases in both input & output impedances
D)
Decrease in input impedance & increase in output impedance

Correct Answer :   Increase in input impedance & decreases in output impedance

54 .
MOSFET can be used as a
A)
Voltage controlled capacitor
B)
Current controlled inductor
C)
Current controlled capacitor
D)
Voltage controlled inductors

Correct Answer :   Voltage controlled capacitor

55 .
An R-C coupled amplifier has mid-frequency gain of 200 and a frequency response from 100 Hz to 20 kHz. A negative feedback network with β = 0.2 is incorporated into the amplifier circuit, the Bandwidth will be
A)
20 kHz
B)
50 kHz
C)
100 kHz
D)
infinite

Correct Answer :   100 kHz

Explaination :

B.W. = fH' - fL' .

56 .
In a commercially available good power supply the voltage regulation is about
A)
1%
B)
5%
C)
10%
D)
20%

Correct Answer :   1%

Explanation : A good power supply does not allow output voltage to vary by more than 1% .

57 .
The most commonly used bias in BJT amplifier circuits is
A)
emitter bias
B)
collector bias
C)
voltage divider bias
D)
collector feedback bias

Correct Answer :   voltage divider bias

Explanation : Voltage divider bias stabilizes Ic.

58 .
In the CE equivalent circuit of figure, the voltage gain is
A)
1000
B)
200
C)
40
D)
5

Correct Answer :   200

Explaination :

59 .
The voltage gain of an amplifier without and with feedback are 100 and 20. The negative feedback is
A)
5%
B)
4%
C)
20%
D)
80%

Correct Answer :   4%

Explanation :

60 .
A potential of 7 V is applied to a silicon diode. A resistance of 1 kΩ is also connected in series. If the diode is forward biased, the current in the circuit is
A)
0
B)
0.7 mA
C)
6.3 mA
D)
7 mA

Correct Answer :   6.3 mA

Explanation :

61 .
In a two stage CE amplifier circuit, the ac collector resistance of the first stage depends on
A)
load resistance
B)
input impedance of first stage
C)
Both (A) and (B)
D)
input impedance of second stage

Correct Answer :   input impedance of second stage

Explanation : Since the first amplifier is feeding the second stage, the input impedance of second stage is the ac collector resistance of first stage.

62 .
In a CE amplifier the ac cut off voltage is 9 V and slope of ac load line is - 0.5 mA/V. The ac saturation current is
A)
4.5 mA
B)
9 mA
C)
18 mA
D)
36 mA

Correct Answer :   4.5 mA

Explanation : AC saturation current is cutoff voltage x slope of ac load line.

63 .
In a CE amplifier the collector resistance is short circuited. The ac output voltage will
A)
increases
B)
decreases
C)
remains the same
D)
increases or decreases

Correct Answer :   decreases

Explanation : Since the output is taken across collector resistance, short-circuiting collector resistance will decrease output voltage.

64 .
The dc load current in a bridge rectifier circuit is 10 mA. The dc load current through each diode is
A)
5 mA
B)
10 mA
C)
20 mA
D)
40 mA

Correct Answer :   5 mA

Explanation : Since both diodes contribute equal load current, each diode current is 5 mA.

65 .
An oscillator requires an amplifier
A)
with equal feedback
B)
with negative feedback
C)
with positive feedback
D)
with either positive or negative feedback

Correct Answer :   with positive feedback

Explanation : Positive feedback is necessary for sustained oscillations.

66 .
The disadvantage of direct coupled amplifiers is
A)
drift
B)
low voltage gain
C)
large size of transistor
D)
None of the above

Correct Answer :   drift

Explanation : The drift is amplified by different stages.

67 .
A transistor has a power rating of 8 W for a case temperature of 25°C. If derating factor is 30 mW/°C, the power rating for 55°C, case temperature is
A)
8 W
B)
7.5 W
C)
7.1 W
D)
6.8 W

Correct Answer :   7.1 W

Explanation :

Power rating = 8 - (55 - 25)(30 x 10-3) = 7.1 W.

68 .
An ideal power supply has
A)
high output resistance
B)
zero internal resistance
C)
very high internal resistance
D)
None of the above

Correct Answer :   zero internal resistance

Explanation : An ideal power supply should have zero voltage drop.

69 .
A P-channel MOSFET operating in the enhancement mode is characterized by Vt = - 4 V and IDQ = - 10 mA, when VGSQ = - 5.5 V, what will be VGSQ if IDQ = -15 mA and ID, on = - 16 mA
A)
- 2 V
B)
1.3 V
C)
3 V
D)
0.13 V

Correct Answer :   0.13 V

Explaination :

70 .
In a self bias circuit for CE amplifier, the emitter resistance is made three times the original value. The collector current will
A)
decrease
B)
remain the same
C)
become three times
D)
become one-third

Correct Answer :   become one-third

Explanation : The emitter current becomes one-third since collector current in BJT is almost the same as emitter current, collector current also becomes one-third.

71 .
A voltage tripler circuit and voltage quadrupler circuit use identical components. Then
A)
voltage regulation in both circuits will be same
B)
voltage regulation in both may or may not be same
C)
voltage regulation in quadrupler circuit will be better than in tripler circuit
D)
voltage regulation in quadrupler circuit will be poorer than in tripler circuit

Correct Answer :   voltage regulation in quadrupler circuit will be poorer than in tripler circuit

Explanation : Since voltage quadrupler circuit uses more components, voltage drop will be more and voltage regulation poorer.

72 .
In a power amplifier the collector current flows for 270° of the input cycle. The operations is
A)
class A
B)
class B
C)
class AB
D)
class C

Correct Answer :   class AB

Explanation : In class A operation IC exists for 360°. In class B operation IC exists for 180°. In between there is the class AB.

73 .
An amplifier has input impedance of 4 kΩ and output impedance of 80 kΩ. It is used in negative feedback circuit with 10% feedback. If open loop gain is 90, the closed loop input and output impedances are
A)
40 kΩ and 8 kΩ respectively
B)
8 kΩ and 160 kΩ respectively
C)
4 kΩ and 80 kΩ respectively
D)
0.4 kΩ and 800 kΩ respectively

Correct Answer :   40 kΩ and 8 kΩ respectively

Explaination :

74 .
In a negative feedback amplifier A = 100, β = 0.04 and Vs = 50 mV, then feedback will be
A)
2
B)
4
C)
8
D)
10

Correct Answer :   4

Explaination : Feed back factor (βA) = 4.

75 .
A voltage doubler circuit is fed by a voltage Vm sin ωt. The output voltage will be nearly 2 Vm only if
A)
load resistance is small
B)
load resistance is large
C)
load resistance is neither small nor large
D)
Either (A) or (C)

Correct Answer :   load resistance is large

Explaination : If load resistance is large, current would be low and voltage drop would be low.

76 .
The purpose of connecting a coupling capacitor in the output circuit of an amplifier is
A)
to block dc collector voltage
B)
to increase voltage gain
C)
to increase collector current
D)
All of the above

Correct Answer :   to block dc collector voltage

Explanation : Capacitor acts for ac or dc.

77 .
A change in the value of the emitter resistance Re in a differential amplifier
A)
Affects the difference mode gain Ad
B)
Affects the common mode gain Ac
C)
Affects both Ad and Ac
D)
Does not effect either Ad and Ac

Correct Answer :   Affects the common mode gain Ac

78 .
The bandwidth of an RF tuned amplifier is dependent on
A)
Quiescent operating point
B)
Q-factor of the tuned input circuit
C)
Q-factor of the tuned output circuit
D)
Q-factor of the output and input circuits as well as quiescent operating point

Correct Answer :   Q-factor of the tuned output circuit

79 .
The MOSFET switch in its onstate may be considered equivalent to
A)
Capacitor
B)
Battery
C)
Resistor
D)
Inductor

Correct Answer :   Capacitor

80 .
Introducing a resistor in the emitter of a common amplifier stabilizes the dc operating point against variations in
A)
Only the temperature
B)
Only the β of the transistor
C)
Both Temperature & β
D)
None of the above

Correct Answer :   Both Temperature & β

81 .
Which component is allowed to pass through it by a choke filter?
A)
Ac
B)
Dc
C)
Both Dc and Ac
D)
Only high frequency Ac

Correct Answer :   Dc

Explanation : XL is zero for dc.

82 .
In the graphical analysis of CE amplifier circuit, the upper end of load line is called
A)
Q point
B)
cut off point
C)
Both (A) and (B)
D)
saturation point

Correct Answer :   saturation point

Explanation : Current is maximum at saturation point.

83 .
A full wave rectifier supplies a load of 1 kΩ. The a.c. Voltage applied to the diodes is 220 - 0 - 220 Volts rms. If diode resistance is neglected, then Average d.c. Voltage
A)
0 volts
B)
198 V
C)
200 V
D)
220 V

Correct Answer :   198 V

Explaination :

84 .
In a transistor leakage current mainly depends on
A)
Temperature
B)
Size of emitter
C)
Doping of base
D)
Rating of transistor

Correct Answer :   Temperature

85 .
The early effect in a bipolar junction transistor is caused by
A)
Fast turn-on
B)
Fast turn-off
C)
Large collector-base reverse bias
D)
Large emitter-base forward bias

Correct Answer :   Large collector-base reverse bias

86 .
Most of the linear ICs are based on the two-transistor differential amplifier because of its
A)
High CMRR
B)
High voltage gain
C)
High input resistance
D)
Input voltage dependent linear transfer characteristic

Correct Answer :   High CMRR

87 .
In a full wave rectifier circuit using centre tapped transformer, the peak voltage across half the secondary winding is 40 V. If diodes are ideal, the average output voltage is
A)
2.55 V
B)
20 V
C)
25.5 V
D)
40 V

Correct Answer :   25.5 V

Explaination :

88 .
In a self bias circuit for CE amplifier, an increase in emitter resistance RE results in
A)
increase in emitter voltage
B)
decrease in emitter current
C)
increase in emitter current
D)
decrease in emitter voltage

Correct Answer :   decrease in emitter current

Explanation : Emitter voltage is the same. Increase of emitter resistance decreases with emitter current.

89 .
For a BJT if β = 50, ICEO = 3 μA and IC = 1.2 mA then IE
A)
1 mA
B)
1.2 mA
C)
1.3 mA
D)
1.4 mA

Correct Answer :   1.2 mA

Explaination :

IE = IC + IB .

90 .
When the circuit is switched on, the loop gain of a Wien bridge oscillator is
A)
about 0.5
B)
1
C)
less than 1
D)
more than 1

Correct Answer :   more than 1

Explanation : The initial loop gain must be more than 1.

91 .
The horizontal intercept of dc load line is the same as ideal
A)
Operating point
B)
Saturation point
C)
Cut off point
D)
Quasi saturation point

Correct Answer :   Cut off point

92 .
A differential amplifier is invariably used in the input stage of all OP-amps. This is dome basically to provide the OP-amps with a very high
A)
CMRR
B)
Slew rate
C)
Bandwidth
D)
Open-loop gain

Correct Answer :   CMRR

93 .
It is desired to reduce distortion in a CE amplifier circuit. We should
A)
reduce ac base voltage
B)
reduce emitter current
C)
reduce collector current
D)
reduce base emitter voltage

Correct Answer :   reduce base emitter voltage

94 .
For a push pull circuit the most favoured biasing method is
A)
self bias
B)
emitter bias
C)
diode bias
D)
collector bias

Correct Answer :   diode bias

95 .
In a N-P-N transistor, when emitter junction is forward biased and collector junction is reverse biased, the transistor will operate in
A)
cut of region
B)
active region
C)
inverted region
D)
saturation region

Correct Answer :   active region

96 .
The advantage of Weinbridge oscillator over the phase shift oscillator is that oscillator the frequency may be varied over a range of
A)
1 : 2
B)
1 : 3
C)
1 : 5
D)
1 : 10

Correct Answer :   1 : 10

97 .
An inverting amplifier has R1 = 10 kΩ, and Rf = 150 kΩ then the O/P voltage, if input voltage Vi = 1 volt.
A)
15 V
B)
-10 V
C)
-14 V
D)
-15 V

Correct Answer :   -15 V

98 .
IF VCC = 15 V, VCEQ = 5 V and ICQ = 50 mA, the efficiency in class A operation is
A)
16.7%
B)
25%
C)
50%
D)
100%

Correct Answer :   16.7%

99 .
Which of the following best represents the bandwidth of an actual op-amp?
A)
0 Hz to 100 kHz
B)
0 Hz to infinity
C)
0 Hz to 10 MHz
D)
100 Hz to 1 MHz

Correct Answer :   0 Hz to 100 kHz

100 .
In a class C operation VCC = 40 V, RL = 50 Ω. The maximum load power can be
A)
8 W
B)
16 W
C)
32 W
D)
64 W

Correct Answer :   16 W

101 .
For an ideal noise free transistor amplifier the noise factor is
A)
zero
B)
1 dB
C)
zero dB
D)
depends on other factors

Correct Answer :   zero dB

102 .
Ultra high frequency oscillators work in the range
A)
20 Hz to 20 kHz
B)
1 kHz to 30 kHz
C)
30 kHz to 30 MHz
D)
above 30 MHz

Correct Answer :   above 30 MHz

103 .
N-channel FETs are superior to p-channel FETs because
A)
they consume less power
B)
mobility of electrons is greater than that of holes
C)
they have high switching time
D)
mobility of electrons is smaller than that of holes

Correct Answer :   mobility of electrons is greater than that of holes

104 .
In a N-P-N transistor, when emitter junction is forward biased and collector junction is reverse biased the transistor will operate in
A)
active region
B)
cut-off region
C)
inverted region
D)
saturation region

Correct Answer :   active region

105 .
A Wien bridge is suitable for
A)
audio frequencies only
B)
radio frequencies only
C)
very low frequencies only
D)
both audio and radio frequencies

Correct Answer :   audio frequencies only

106 .
Asource follower using an FET usually has a voltage gain which is
A)
Exactly unity but negative
B)
About -10
C)
Greater than +100
D)
Slightly less than unity but positive

Correct Answer :   Greater than +100

107 .
Three identical amplifiers with each one having a voltage gain of 50,input resistance of 1KΩ & output resistance of 250, are cascaded. The open circuit voltage gain of combined amplifier is
A)
49dB
B)
51dB
C)
98dB
D)
102dB

Correct Answer :   98dB

108 .
A dc power supply has no-load voltage of 30v,and a full-load voltage of 25v at full-load current of 1A.Its output resistance & load regulation ,respectively are
A)
5 Ω & 20 %
B)
25 Ω & 20 %
C)
5 Ω & 16.7 %
D)
25 Ω & 16.7 %

Correct Answer :   25 Ω & 20 %

109 .
In an OP-amp differentiator
A)
The amplitude of output is proportional to input
B)
Output occurs when input is finite and constant
C)
Polarity of input and output is the same
D)
The amplitude of output is proportional to rate of change of input

Correct Answer :   The amplitude of output is proportional to rate of change of input

110 .
Which op-amp circuit uses a capacitor in series with input and resistance in feedback path?
A)
Integrating amplifier
B)
Differentiating amplifier
C)
Logarithmic amplifier
D)
None of the above

Correct Answer :   Differentiating amplifier

111 .
For class B operation the theoretical maximum efficiency is
A)
25.5%
B)
50%
C)
78.5%
D)
100%

Correct Answer :   78.5%

112 .
Typical values of current gains for CE, CB and CC amplifiers are
A)
120, 1 and 120 respectively
B)
1, 1 and 120 respectively
C)
1, 120 and 120 respectively
D)
120, 120 and 1 respectively

Correct Answer :   120, 1 and 120 respectively

113 .
To draw ac equivalent circuit for a CE amplifier we should
A)
Short all capacitors
B)
Reduce all dc sources to zero
C)
Reduce all dc sources to zero and open all capacitors
D)
Reduce all dc sources to zero and short all capacitors

Correct Answer :   Reduce all dc sources to zero and short all capacitors

114 .
In a transistor amplifier, the reverse saturation current ICO
A)
Increase 100°C with temperature
B)
Doubles for every 10°C rise in temperature
C)
Doubles for every 5°C rise in temperature
D)
Doubles for every 20°C rise in temperature

Correct Answer :   Doubles for every 10°C rise in temperature

115 .
When the emitter current of a transistor is changed by 1 mA, its collector current changes by 0.990 mA. The common-emitter short-circuit current gain is
A)
1
B)
9.9
C)
99
D)
199

Correct Answer :   99

116 .
In a crystal oscillator of the Colpitt's oscillator type, the crystal is put is place of the
A)
inductor L
B)
resistor R1
C)
condenser C1
D)
condenser C2

Correct Answer :   inductor L

117 .
Astable multivibrator has
A)
one stable state
B)
two stable state
C)
two quasi-stable states
D)
one quasi stable state

Correct Answer :   two quasi-stable states

118 .
Most small signal transistors are
A)
P-N-P, silicon, in a plastic package
B)
N-P-N, silicon, in a plastic package
C)
P-N-P, germanium in a metallic case
D)
N-P-N, germanium in a metallic case

Correct Answer :   N-P-N, silicon, in a plastic package

119 .
A FET is a better clapper than a BJT because it has
A)
lower input current
B)
lower off-set voltage
C)
higher input impedance
D)
higher series ON resistance

Correct Answer :   lower off-set voltage

120 .
The input gate current of FET is closer to
A)
few amperes
B)
few milli amperes
C)
few microamperes
D)
negligibly smaller value

Correct Answer :   negligibly smaller value

121 .
When a 1 V increase in gate voltage changes the drain current 10 mA in an FET, its gm equals
A)
10 μμ
B)
100 μμ
C)
1000 μμ
D)
10000 μμ

Correct Answer :   10000 μμ

122 .
Class AB operation is often used in power large signal) amplifiers in order to
A)
Overcome a crossover distortion
B)
Get maximum efficiency
C)
Remove even harmonics
D)
Reducing collector dissipation

Correct Answer :   Overcome a crossover distortion

123 .
Which of the following amplifier circuit using junction transistor has the best gain?
A)
Common base
B)
Common collector
C)
Common emitter
D)
All have the same gain

Correct Answer :   Common emitter

124 .
When a transistor is connected in common emitter mode, it with have
A)
High input resistance and low output resistance
B)
Medium input resistance and high output resistance
C)
Low input resistance as well as output resistance
D)
Negligible input resistance and high output resistance

Correct Answer :   Medium input resistance and high output resistance

125 .
Which of the following statements is false?
A)
Push pull signals are equal and opposite in phase
B)
A push pull output transformer has a centre-tapped primary
C)
Class AB operation cannot be used for a push pull audio power output phase
D)
All of the above

Correct Answer :   Class AB operation cannot be used for a push pull audio power output phase

126 .
A sine wave is passed through an amplifier which severely limits it symmetrically. If then passes to a second amplifier which is narrow band and tuned to the frequency of the original sine wave. What will be the output wave from this second amplifier?
A)
A square wave of double the frequency of that of original sine wave
B)
A sine wave of constant amplitude at the frequency of the original sine wave
C)
A square wave of the same frequency as that of the original sine wave
D)
A sine wave of constant amplitude at double frequency of the original sine wave

Correct Answer :   A sine wave of constant amplitude at the frequency of the original sine wave

127 .
In which configuration is ac collector voltage zero?
A)
CC
B)
CB
C)
CE
D)
None of the above

Correct Answer :   CC

128 .
The properties of FETs closely resemble those of a
A)
UJT
B)
P-N-P transistor
C)
N-P-N transistor
D)
thermionic valve

Correct Answer :   thermionic valve

129 .
In a transistor which of the following region is very lightly doped and is very thin?
A)
Base
B)
Emitter
C)
Collector
D)
None of the above

Correct Answer :   Base

130 .
The purpose of providing groundings rings with MOSFET is to
A)
ground all eddy currents
B)
protect against any descaling
C)
protect against any physical injury
D)
avoid any stray voltage at the gate that may destroy SiO2 layer

Correct Answer :   avoid any stray voltage at the gate that may destroy SiO2 layer

131 .
Self bias is an example of __________ feedback that tends to stabilize the drain current against changes in temperature and JFET replacement.
A)
low
B)
negative
C)
positive
D)
variable

Correct Answer :   negative

132 .
The minimum value of hfe of a transistor used in RC phase shift oscillator is
A)
29
B)
44.5
C)
45.4
D)
54.4

Correct Answer :   44.5

133 .
The RC network of wein bridge oscillator consists of resistors and capacitors of values R = 220 kΩ and C = 250 PF Determine the frequency of oscillation
A)
2.98 kHz
B)
2 kHz
C)
3 kHz
D)
10 kHz

Correct Answer :   2.98 kHz

134 .
Which of the following statement is correct?
A)
FET and junction transistor both are bipolar
B)
FET and junction transistor both are unipolar
C)
The FET is bipolar, while junction transistor are unipolar
D)
The FET is unipolar, while junction transistor are bipolar

Correct Answer :   The FET is unipolar, while junction transistor are bipolar

135 .
Which of the following method cannot be used to increase the bandwidth for cascaded RF amplifier stages?
A)
Stagger tuning
B)
Wave traps in each stage
C)
Doubled tuned transformers with tighter coupling
D)
A shunt damping resistor across each tuned circuit

Correct Answer :   Wave traps in each stage

136 .
The effective channel length of a MOSFET in a saturation decreases with increase in
A)
Body voltage
B)
Gate voltage
C)
Drain voltage
D)
Source voltage

Correct Answer :   Drain voltage

137 .
In all base driver amplifiers
A)
ac collector voltage is in phase with ac base voltage
B)
ac emitter voltage is 180° out of phase with ac base voltage
C)
ac collector voltage is 180° out of phase with ac base voltage
D)
None of the above

Correct Answer :   ac collector voltage is 180° out of phase with ac base voltage

138 .
The encapsulation of transistor is necessary for
A)
Mechanical ruggedness
B)
Preventing radio interference
C)
Avoiding loss of free electrons
D)
Preventing photo-emission effects

Correct Answer :   Mechanical ruggedness

139 .
In deriving ac equivalent circuit for an amplifier circuit we short circuit
A)
All resistors
B)
All inductors
C)
All transistors
D)
All capacitors

Correct Answer :   All capacitors

140 .
Thermal runaway is not possible in FET because as the temperature of FET increases
A)
The drain current increases
B)
The mobility decreases
C)
The transconductance increases
D)
None of the above

Correct Answer :   The mobility decreases

141 .
Class A and Class B power amplifiers predominate at
A)
all frequencies
B)
radio frequencies
C)
audio frequencies
D)
audio and radio frequency

Correct Answer :   audio frequencies

142 .
In a CE amplifier, the collector resistance is 6 kΩ and load resistance is 3 kΩ. The ac load resistance is
A)
2 kΩ
B)
3 kΩ
C)
6 kΩ
D)
9 kΩ

Correct Answer :   2 kΩ

143 .
A voltage tripler circuit uses
A)
2 diodes and 2 capacitors
B)
3 diodes and 3 capacitors
C)
2 diodes and 3 capacitors
D)
3 diodes and 2 capacitors

Correct Answer :   3 diodes and 3 capacitors

144 .
One input terminal of high gain comparator circuit is connected to ground and a sinusoidal voltage is applied to the other input. The output of comparator will be
A)
sinusoidal
B)
half rectified sinusoidal
C)
full rectified sinusoidal
D)
square wave

Correct Answer :   square wave

145 .
3N 200 is a
A)
UJT
B)
P-N-P transistor
C)
dual gate MOSFET
D)
semi-conductor diode

Correct Answer :   dual gate MOSFET

146 .
The A.C. resistance of the emitter diode will be
A)
5.05 Ω
B)
50.5 Ω
C)
505 Ω
D)
5050 Ω

Correct Answer :   50.5 Ω

147 .
In a P-N-P junction transistor as compared to base region is more heavily doped so that
A)
leakage current is minimized
B)
recombination will be increased in the base region
C)
the flow across the base regional is only because of electrons
D)
the flow across the base region is mainly because of holes

Correct Answer :   the flow across the base region is mainly because of holes

148 .
In every practical oscillator the loop gain is slightly more than unit and amplitude of oscillations is limited by
A)
β
B)
magnitude of gain
C)
onset of non-linearity
D)
magnitude of loop gain

Correct Answer :   onset of non-linearity

149 .
Which of the following is not valid in case of FETs?
A)
It has fast switching time
B)
It has low voltage gain
C)
It has high input impedance
D)
It is voltage controlled device

Correct Answer :   It has fast switching time

150 .
When the emitter current of a transistor is changed by 1 mA, its collector current changes by 0.990 mA. The common base short circuit current gain a for the transistor is
A)
0.99
B)
0.990
C)
1.01
D)
1.001

Correct Answer :   0.99

151 .
Which of the following device acts as an N-P-N and a P-N-P transistor connected base to base and emitter to controller?
A)
Diac
B)
SCR
C)
Triac
D)
UJT

Correct Answer :   SCR

152 .
Which of the following statement about TRIAC is incorrect?
A)
Any one of its main terminals can be used either as cathode or as anode
B)
It can be triggered in response to both positive and negative gate terminals
C)
It is not particularly suited to A.C. or mains power control
D)
None of the above

Correct Answer :   It is not particularly suited to A.C. or mains power control

153 .
A half wave diode rectifier and full wave diode bridge rectifier both have an input frequency of 50 Hz. The frequencies of outputs respectively are
A)
50 Hz each
B)
50 Hz and 100 Hz
C)
100 Hz each
D)
100 Hz and 50 Hz

Correct Answer :   50 Hz and 100 Hz

154 .
The knee voltages in silicon and germanium diodes respectively are
A)
0.3 V each
B)
0.3 V and 0.7 V
C)
0.7 V each
D)
0.7 V and 0.3 V

Correct Answer :   0.7 V and 0.3 V

155 .
In a transistor βdc is likely to vary between 100 and 400. The proper value of βdc to be used to located Q point is
A)
100
B)
200
C)
250
D)
400

Correct Answer :   200

156 .
Which of the following noise becomes of great importance at high frequencies?
A)
Shot noise
B)
Flicker noise
C)
Agitation noise
D)
Transit time noise

Correct Answer :   Transit time noise

157 .
In a full wave voltage doubler circuit, the input frequency is 560 Hz. The ripple frequency is
A)
25 Hz
B)
50 Hz
C)
100 Hz
D)
200 Hz

Correct Answer :   100 Hz

158 .
In a self bias circuit for CE amplifier the collector supply voltage is made twice. The collector current will
A)
decrease
B)
increase
C)
remain the same
D)
increase or decrease

Correct Answer :   increase

159 .
In an amplifier, if the output current flows for 120° of the input cycle, the class of amplifier will be
A)
A
B)
B
C)
C
D)
AB

Correct Answer :   C

160 .
Which op-amp circuit uses a diode as one of the circuit components?
A)
Logarithmic amplifier
B)
Summing amplifier
C)
Integrating amplifier
D)
Differentiating amplifier

Correct Answer :   Logarithmic amplifier

161 .
For a transistor to have-a larger β it must have and a
A)
close to 0.5
B)
close to zero
C)
nearly infinite
D)
close to unity

Correct Answer :   close to unity

162 .
JFET is also known as
A)
square law device
B)
linear device
C)
inverse law device
D)
logarithmic law device

Correct Answer :   square law device

163 .
Drain feedback bias is often used with
A)
D MOSFETs
B)
E MOSFETs
C)
Both D and E MOSFETs
D)
Neither D nor E MOSFETs

Correct Answer :   E MOSFETs

164 .
In a CE amplifier circuit the emitter by pass capacitor is remove. The ac output voltage
A)
increases
B)
decreases
C)
remains the same
D)
increases or decreases

Correct Answer :   decreases

165 .
In a differential amplifier, CMRR can be improved by using an increased
A)
source resistance
B)
collector resistance
C)
emitter resistance
D)
power supply voltages

Correct Answer :   emitter resistance

166 .
Pick the odd-one out
A)
Clapp oscillator
B)
Colpitt oscillator
C)
Hartley Oscillator
D)
Weinbridge oscillator

Correct Answer :   Weinbridge oscillator

167 .
In a CE amplifier the output coupling capacitor is short circuited. The dc collector voltage
A)
will decrease
B)
will increase
C)
will remain the same
D)
may increase or decrease

Correct Answer :   will decrease

168 .
If 1.5% of the output of an amplifier is feedback positively to the input, the minimum gain required of the amplifier for oscillations to occur, is
A)
16.6
B)
44.4
C)
66.6
D)
75

Correct Answer :   66.6

169 .
The use of a capacitor filter in a rectifier circuit gives satisfactory performance only when the load
A)
voltage is low
B)
current is low
C)
current is high
D)
voltage is high

Correct Answer :   current is low

170 .
A certain transistor has adc of 0.98 and a collectors leakage current of 5 μA. If IE = 1 mA, the collector current will be
A)
0.955 mA
B)
0.975 mA
C)
0.985 mA
D)
1.005 mA

Correct Answer :   0.985 mA

171 .
The input resistance R, of an ideal voltage amplifier is __________ and that of a current amplifier is __________ .
A)
zero, zero
B)
infinite, zero
C)
zero, infinite
D)
infinite, infinite

Correct Answer :   infinite, zero

172 .
A major advantage of TWT over a Klystron lies in its
A)
higher gain
B)
higher output
C)
higher frequency
D)
higher bandwidth

Correct Answer :   higher gain

173 .
The heat sink disposes off heat mainly by
A)
radiation
B)
conduction
C)
forced convection
D)
natural convection

Correct Answer :   natural convection

174 .
When narrow current pulses drive a high Q resonant circuit the voltage across the circuit looks like
A)
narrow pulses
B)
half sine wave
C)
almost sine wave
D)
Either (A) or (B)

Correct Answer :   almost sine wave

175 .
The multivibrator circuit that has a typical application of converting sinusoidal input into a square wave output is
A)
emitter coupled binary
B)
monoshot multivibrator
C)
free-running multivibrator
D)
Schmitt trigger

Correct Answer :   Schmitt trigger

176 .
The feedback resistance rd in small signal model of MOSFET is of the order of
A)
1 KΩ
B)
1 MΩ
C)
100 Ω
D)
1000 MΩ

Correct Answer :   1000 MΩ

177 .
Which amplifier has a voltage gain of less than 1?
A)
Common base
B)
Common collector
C)
Common emitter
D)
Both CB and CC

Correct Answer :   Common collector

178 .
For holding the drain current constant in spite of large changes in JFET parameters
A)
current source bias is used
B)
reverse bias is used
C)
no bias is used
D)
voltage divider bias is used

Correct Answer :   current source bias is used

179 .
The main disadvantage of a JFET is
A)
low gain
B)
high cost
C)
high noise level
D)
low gain-bandwidth product

Correct Answer :   low gain-bandwidth product

180 .
Low frequency response of amplifier is mainly limited by
A)
input capacitor
B)
output capacitor
C)
bypass capacitor
D)
biasing capacitor

Correct Answer :   bypass capacitor

181 .
As compared to a bipolar transistor, a JFET is
A)
more sensitive to changes in input voltage
B)
highly sensitive to changes in input voltage
C)
less sensitive to changes in input voltage
D)
equally sensitive to changes in input voltage

Correct Answer :   less sensitive to changes in input voltage

182 .
In a bistable multivibrator, commutating capacitors are used to
A)
provide ac coupling
B)
increase the speed of response
C)
increase the base storage charge
D)
alter the frequency of the output

Correct Answer :   increase the speed of response

183 .
In a CE amplifier the ac signal is increased. Which of the following will not change?
A)
Ac emitter voltage
B)
Ac base voltage
C)
Ac collector voltage
D)
Ac collector voltage and ac emitter voltage

Correct Answer :   Ac emitter voltage

184 .
A Darlington circuit is obtained by connecting
A)
two CE stages in cascade
B)
two CB stages in cascade
C)
two emitter follower in cascade
D)
a CE stages followed by CB stage

Correct Answer :   two CB stages in cascade

185 .
A CE amplifier has a high input signal. In the wave shape of emitter current
A)
positive and negative half cycles will be symmetrical
B)
the half cycles may be either elongated or compressed
C)
positive half cycle will be compressed and negative half cycle will be elongated
D)
positive half cycle will be elongated and negative half cycle will be compressed

Correct Answer :   positive half cycle will be elongated and negative half cycle will be compressed

186 .
An inverting voltage feedback is a
A)
current amplifier
B)
voltage amplifier
C)
current to voltage converter
D)
voltage to current converter

Correct Answer :   current to voltage converter

187 .
In a CE amplifier the Q point is very close to cutoff point on the load line. This results in
A)
cut off clipping
B)
saturation clipping
C)
both saturation and cut off clipping
D)
either saturation clipping or cut off clipping

Correct Answer :   cut off clipping

188 .
A cascade amplifier will have higher cut off frequency
A)
less than that of single stage amplifier
B)
equal to that of single stage amplifier
C)
more than that of single stage amplifier
D)
None of the above

Correct Answer :   less than that of single stage amplifier

189 .
In oscillator circuits the energy feedback to its input terminal from output is
A)
90° out of phase with the input signal
B)
180° out of phase with the input signal
C)
270° out of phase with the input signal
D)
always in phase with the input signal

Correct Answer :   180° out of phase with the input signal

190 .
Occasionally a discrete amplifier user RF chokes instead of collector resistors. Such amplifiers are inherently
A)
low pass amplifiers
B)
high pass amplifiers
C)
band pass amplifiers
D)
None of the above

Correct Answer :   high pass amplifiers

191 .
Which of the following number specification refers to FET with one gate?
A)
2N
B)
3N
C)
3X
D)
3Y

Correct Answer :   3N

192 .
The emitter follower steps up the impedance by a factor of
A)
α
B)
β
C)
α β
D)
α / β

Correct Answer :   β

193 .
A dc amplifier can operate
A)
at zero frequency
B)
only at low frequency
C)
only at high frequencies
D)
both at low and high frequencies

Correct Answer :   at zero frequency

194 .
In applications where __________ input resistance is needed, the JFET is preferred to the bipolar transistor.
A)
zero
B)
low
C)
high
D)
very low

Correct Answer :   high

195 .
In the circuit shown in the figure, the approximate voltage at the transistor,
A)
base and collector respectively are -8 V and -5 V
B)
base and emitter respectively are -8 V and -7.3 V
C)
Collector and emitter respectively are -5 V and -7.3
D)
base, emitter and collector respectively are -8 V, 7.3 V and -5 V

Correct Answer :   base, emitter and collector respectively are -8 V, 7.3 V and -5 V

196 .
In a P-N-P transistor, with normal bias, the emitter junction
A)
remains open
B)
offers a low resistance
C)
is always reverse biased
D)
offers very high resistance

Correct Answer :   offers a low resistance

197 .
Primary advantage of a crystal oscillator is that
A)
it gives a high O/P voltage
B)
it can oscillate at any frequency
C)
it operates on a very low dc supply voltage
D)
its frequency of oscillation remains almost constant

Correct Answer :   its frequency of oscillation remains almost constant

198 .
The conversion or collector circuit efficiency is a measure
A)
how much distortion in output is reduced with respect to input
B)
how successfully the active device converts A.C. power to D.C. signal power
C)
how successfully the active device converts D.C. power to A.C. signal power
D)
None of the above

Correct Answer :   how successfully the active device converts D.C. power to A.C. signal power

199 .
A transistor amplifier is operating in class A mode. If a transformer is connected for impedance matching, the efficiency will
A)
increase
B)
decrease
C)
Not be affected
D)
increase or decrease

Correct Answer :   increase

200 .
The pinch-off voltage is the drain voltage on the shorted gate drain curve above which the drain current becomes
A)
very high
B)
almost constant
C)
highly variable
D)
almost negligible

Correct Answer :   almost constant

201 .
A transconductance amplifier has
A)
high input and output impedance
B)
low input and output impedance
C)
high input impedance and low output impedance
D)
low input impedance and high output impedance

Correct Answer :   high input and output impedance

202 .
In order to protect a MOSFET against damage from any stray voltage at the gate
A)
terminals are shorted
B)
grounding rings are provided
C)
Both (A) and (B)
D)
source terminal is earthed during transit

Correct Answer :   source terminal is earthed during transit

203 .
RECTIFIER : OSCILLATOR ::
A)
DC : AC
B)
Regulation : Efficiency
C)
Capacitance : Inductance
D)
Series resonance : Parallel resonance

Correct Answer :   Regulation : Efficiency

204 .
Which amplifier will be preferred for highest gain?
A)
Darlington's pair
B)
Single stage amplifier
C)
Cascade amplifier
D)
Depends on the circuitry

Correct Answer :   Cascade amplifier

205 .
Which of the following are synonymous?
A)
FET and JFET
B)
P-N-P and N-P-N
C)
JFET and MOSFET
D)
MOSFET and IGEFT

Correct Answer :   MOSFET and IGEFT

206 .
The advantage of using crystal oscillator is that it
A)
works at high frequency
B)
gives high output voltage
C)
requires low d.c. supply voltage
D)
gives constant frequency of oscillations

Correct Answer :   gives constant frequency of oscillations

207 .
Cross-over distortion behaviour is a characteristic of
A)
class A output stage
B)
class B output stage
C)
class AB output stage
D)
common base output stage

Correct Answer :   class B output stage

208 .
A transistor will operate in inverted region when
A)
emitter junction as well as collector junction are reverse biased
B)
emitter junction as well as collector junction are forward biased
C)
emitter junction is reverse biased and collector junction is forward biased
D)
emitter junction is forward biased and collector junction is reverse biased

Correct Answer :   emitter junction is reverse biased and collector junction is forward biased

209 .
An amplifier signal is made up of just two frequencies 1000 Hz. The output signal consists of 500 Hz and 25000 Hz frequencies. This may be attributed to
A)
harmonic distortion
B)
intermodulation distortion
C)
Both (A) and (B)
D)
None of the above

Correct Answer :   intermodulation distortion

210 .
One of the major applications of JFET is in
A)
switching
B)
constant voltage-source
C)
constant current-source
D)
electron flow regulation

Correct Answer :   switching

211 .
A Hartley oscillator uses
A)
a tapped inductor
B)
a tapped capacitor
C)
a tapped inductor for inductive feedback
D)
None of the above

Correct Answer :   a tapped inductor for inductive feedback

212 .
Aperture circuit produces __________ in sample hold circuit.
A)
the total sampling time
B)
time required by holding capacitor to reach upto the level close to input
C)
the time taken by O/P to settle within the specified 1% error band, that of the I/P
D)
delay between the instance at which hold command is initiated and the instance at which O/P starts tracking I/P

Correct Answer :   delay between the instance at which hold command is initiated and the instance at which O/P starts tracking I/P

213 .
The circuit in figure is
A)
positive clamper
B)
negative clamper
C)
positive peak clipper
D)
negative peak clipper

Correct Answer :   positive clamper

214 .
A pulse transformer uses
A)
air core
B)
ferrite core
C)
iron core
D)
copper core

Correct Answer :   ferrite core

215 .
The main drawback in the performance of shunt peaked wide band amplifier is
A)
poor phase response
B)
two low gain at low frequency
C)
reduce frequency at middle frequency
D)
that the maximum gain of the stage is small

Correct Answer :   poor phase response

216 .
In a CE amplifier circuit
A)
Q point lies on dc load line
B)
Q point lies on ac load line
C)
Q point must lie on both dc and ac load lines
D)
Q point lies may or may not lie on both dc and ac load lines

Correct Answer :   Q point must lie on both dc and ac load lines

217 .
The semi-conductor type 2 N 34 indicates
A)
a JFET
B)
a n-channel MOSFET
C)
a diode with two electrodes
D)
a diode with three electrodes

Correct Answer :   a diode with two electrodes

218 .
In saturation region JFET acts like a
A)
switch
B)
resistance
C)
short circuit
D)
bipolar device

Correct Answer :   resistance

219 .
Which of the following are difficult to be fabricated in a monolithic IC?
A)
Inductors
B)
Large capacitors
C)
Small capacitors
D)
Both (A) and (B)

Correct Answer :   Both (A) and (B)

220 .
In an op-amp a common mode signal is applied to
A)
inverting terminal
B)
non-inverting terminal
C)
both terminals
D)
one or both the terminals

Correct Answer :   both terminals

221 .
Which of the following op-amp circuits has zero resistance in the feedback path?
A)
Source follower
B)
Inverting amplifier
C)
Summing amplifier
D)
Integrating amplifier

Correct Answer :   Source follower

222 .
In an LC filter, the ripple factor,
A)
increases with load current
B)
has the lowest value
C)
increases with load resistance
D)
remains constant with the load current

Correct Answer :   has the lowest value

223 .
Which of the following can be used to isolate a low impedance from a high impedance source?
A)
Darlington pair
B)
Emitter follower
C)
Ï€ filter
D)
Any of the above

Correct Answer :   Emitter follower

224 .
A transistor is said to be in a quiescent state when
A)
the transistor is unbiased
B)
the phase of input and output signal is identical
C)
the amplitude of input and output signal is equal
D)
no signal is applied to the input

Correct Answer :   no signal is applied to the input

225 .
According to Barkhausen criteria in order to sustain the oscillations
A)
loop gain of the circuit must be negligible
B)
the phase shift around the circuit must be 180°
C)
loop gain of the circuit must be equal to unity
D)
None of the above

Correct Answer :   loop gain of the circuit must be equal to unity

226 .
In the above case, what will be the value of capacitor to obtain 100 kHz frequency?
A)
0.0065 pF
B)
0.0130 pF
C)
0.0260 pF
D)
0.520 pF

Correct Answer :   0.0065 pF

227 .
Equal amplitude ac signals are given as inputs to both inverting and given as inputs to both inverting and non-inverting terminals of an op-amp. The output will be zero when the phase difference between inputs is
A)
0°
B)
90°
C)
180°
D)
270°

Correct Answer :   0°

228 .
The noise figure of FET circuit is
A)
independent of the quiescent point
B)
dependent on the quiescent point only
C)
dependent on the triggering mechanism
D)
independent of all above

Correct Answer :   independent of the quiescent point

229 .
In CE approximately, the active region is where the collector curves are
A)
almost vertical
B)
almost horizontal
C)
inclined at 45°
D)
inclined at 60°

Correct Answer :   almost horizontal

230 .
In a CE amplifier the Q point is very close to saturation point on the dc load line. This results in
A)
negative clipping of collector current
B)
positive clipping of collector current
C)
both positive and negative clipping of collector current
D)
either positive or negative clipping of collector current

Correct Answer :   positive clipping of collector current

231 .
In a JFET, gates are always
A)
unbiased
B)
forward biased
C)
reverse biased
D)
either forward or reverse biased

Correct Answer :   reverse biased

232 .
By connecting external resistances to a differential amplifier we can adjust
A)
voltage gain
B)
bandwidth
C)
both voltage gain and bandwidth
D)
None of the above

Correct Answer :   both voltage gain and bandwidth

233 .
The slope of the transfer characteristics of an N-channel JFET is
A)
zero
B)
negative
C)
positive
D)
constantly varying

Correct Answer :   negative

234 .
An engineer designs an amplifier to have a voltage gain of 60, but when constructed it only had a gain of 50. What value of feedback will double the gain?
A)
+1%
B)
+3.3%
C)
+0.5%
D)
+0.66%

Correct Answer :   +1%

235 .
The maximum theoretical efficiency for class A amplifier is
A)
12.5%
B)
25%
C)
50%
D)
75%

Correct Answer :   25%

236 .
The purpose of impedance matching in an amplifier circuit is to achieve
A)
high efficiency
B)
reduce distortion
C)
Both (A) and (B)
D)
maximum power transfer

Correct Answer :   maximum power transfer

237 .
In a BJT CE amplifier circuit the value of coupling capacitor should be such that
A)
its reactance is small for the lowest frequency in the input and output
B)
its reactance is high for the lowest frequency in the input and output
C)
its reactance is zero for the lowest frequency in the input and output
D)
its reactance is infinite for the lowest frequency in the input and output

Correct Answer :   its reactance is small for the lowest frequency in the input and output

238 .
In a CE amplifier it is desired that the signal should be able to swing equally in both directions. Then the Q point should be
A)
at the centre of dc load line
B)
at the centre of collector voltage
C)
at the centre of ac load line
D)
at the centre of collector current

Correct Answer :   at the centre of ac load line

239 .
In a base driver amplifier the voltage gain is the ratio of
A)
ac emitter voltage to ac base voltage
B)
ac collector voltage to ac base voltage
C)
ac base voltage to ac emitter voltage
D)
ac collector voltage to ac emitter voltage

Correct Answer :   ac collector voltage to ac base voltage

240 .
A junction Field Effect Transistor can operate in
A)
depletion mode only
B)
enhancement mode only
C)
depletion and enhancement modes
D)
neither depletion nor enhancement modes

Correct Answer :   depletion mode only