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www.DevilsDuke.comELECTRONIC CIRCUITS ANALYSIS

1) Critical capacitance with smallest equivalent resistance that determines the lower cut off of

CB amplifier is

a) I/P coupling capacitorb) Emitter bypass capacitor if c1 = c2

c) c2 output coupling capacitor

d) None.

2) Non-linear distortion is maximum in a) class

B mode

b) class A mode

c) class AB moded) class C mode

3) typical value of rbb of Ge BJT at room temperature of Ie =1.3ma 100 ohms

4) cascade amplifier is 2- transistor combination has

a) collector of first transistor is connected to the base of second transistor

b) collector current of first transistor is same as emitter current of second transistor

c) emitter current of first transistor is same as the collector current of the second transistor

d) none

5) resultant phase shift of odd no of CE amplifier stages at mid band frequency is a)

3600

b) 1800c) 450

d) 900

6) major drawbacks of Darlington transistor pair is

a) low current gain compared to single emitter follower

b) dependence of AV on transistor selected condition

c) low i /p impedance compared to single emitter followerd) dependence of h-parameters on quiescent point.

7) lower cutoff &higher cutoff frequency of rc coupled amplifier are

a) both zero

b) both infinity

c) zero & infinity respectively

d) similar to those of CE stage


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8) the miller input capacitance in CB AMP IS

a) large compared to miller capacitance in CE

b) very large because of +ve voltage gain in CBc) small because of +ve voltage gain in CBd) is not negligible compare to other capacitance

9) identify the correct relationship

a) falpha ~ fbeta

b) fbeta >> falpha

c) falpha ~ ft

d) falpha >> fbeta

10) final stage of multistage amplifier is generally

a) a pre-amplifierb) a voltage post amplifier

c) a power amplifier

d) a microphone amplifier

11) Max conversion efficiency of a series fed class A power amplifier is

a) 75

b) 100c) 50

d) 25

12) even harmonics are not present in the o/p of

a) class A transformer coupled amplifier

b) class c amplifier

c)class A amplifier

d) class B push pull amplifier

13) voltage gain of an amplifier reduces to 1/(root 2)its max

a) break frequency

b) miller frequencyc) half power frequency

d) cutoff frequency

14) Identify the correct statement regarding the voltage gain of a CE transistor amplifier

a) it increases with increase in ac load Rb) it is independent of ac load R & is large

c) it decreases with increase in ac load R

d) it is always approximately unity


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15) Phase reversal between i/p & o/p signal voltages occurs in

a) common base amplifier

b) common drain amplifier

c) common gate amplifierd) common source amplifier

16) Identify the incorrect statement

[ d ]

a) frequency distortion in an amplifier is mainly due to the reactive component circuit

b) amplitude distortion is also referred to as non-linear distortion

c) distortion in amplifier due to unequal phase shifts at different frequencies is called delay

distortion

d) phase shift distortion is same as frequency distortionans: [D ]

17) Resultant current gain of a Darlington pair individual current gain of h fe is

[ d ]

a) hfe/2

b) hfe

c) 2hfe

d) hfe2

ans: [ D ]

18) o/p voltage of a non ideal differential amplifier is

[ c ]

a) zero

b) Ad Vd

c) (AdVd+ AcVc)d) AcVc

ans: [ C ]

19) rce >> rbe condition is applicable in hybrid -pie equivalent of CE amplifier because

a) collector base junction is reverse biased & emitter base junction is forward biasedb) o/p R is always much larger than i/p R

c) b is the internal base terminal

d) base region is extremely tin compared to emitter & collector terminals

20) expression for short circuit current gain bandwidth

[ d ]


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a) gm/2pie hfe (ce+cc)

b) gm/(ce+cc)

c) gm/ hfe (ce+cc)

d)gm /2pie (ce+cc)ans:[ D ]

21) the parameter with 0c/watt as its units of measurement is

[ a ]

a) thermal expansionb) thermal coefficient

c) thermal resistance

d) thermal power

ans : [ A ]

22) Even harmonics in the o/p are connected in push - pull configurations only if

[ a ]

a) both transistors are perfectly matchedb) both NPN & PNP transistors are used

c) A phase inversion is not used at inputs of 2 transistors

d) two power supplies are used

ans:[ A ]

23) i/p &o/p capacitors in a transistors amplifier are not referred to as[ a ]

a) inter electrode capacitors

b) coupling capacitors

c) blocking capacitors

d) dc de-coupling capacitors

ans : [ A ]

24) FET amplifier configuration , which is similar to CC BJT is

[ b ]

a) common gate amplifier


c) common source amplifier

d) swamped source resistor amplifier

ans:[ B ]

25) identify the expression for voltage gain CE & fet amplifier at low frequency


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[ c ]

a) -gm rd Rl /(rd + Rl)

b) gm rd Rl / ( rd +Rl+ gm rd Rl)c) gm rd Rl /(rd + Rl)d) Rl || rd / (1+ gm rd)

ans: [ C ]

26) Resultant phase shift of even no of CB amplifier stage at frequency below lower cutoff

frequency [ d ]

a) always a multiple of 2 pie

b) product of phase shift introduced by individual stages

c) always 1800

d) sum of the phase shifts introduced by individual stagesans: [ D ]

27) 2-stage rc coupled amplifier is configured as

[ a ]

a) 2 capacitively coupled CE stages cascadedb) a CE stage capacitively coupled to a CC stage

c) 2 capacitively coupled CB stages cascaded.

d) 2 capacitively coupled CC stages cascaded

ans: [ A ]

28) Identify the incorrect statement for a high frequency hybrid pie model of a BJT is

[ a ]

a) high frequency hybrid pie capacitances can be expressed in terms of low

frequency h- parametersb) capacitance between collector & base terminal of a BJT is called overlap -diode capacitance

c) ' B' represent internal base terminal

d) high frequency hybrid pie conductances can be expressed in terms of low frequency h-

parameters.

ans:[ A ]

29) identify false statement

[ c ]

a) fbeta & Ic exhibits a peak value of a particular ic.

b) unity gain band width Ft is the function of Ic

c)ft & Ic both are functions of fbeta


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d) Ft variation with Ic is similar to hfe variation with T

ans: [ C ]

30) during the mid band frequency the gain of amplifier is[ d ]

a) 1/(root 2) times Max value

b) min

c)unity

d) constantans: [ D ]

31) CB amplifier of BJT is similar in behaviour with following FET configuration

[ a ]

a)common gate amplifier


C) common source amplifier

d)swamped source resistor amplifier

ans:[ A ]

32) 2-transistor cascade with both collectors tied together & emitter of the transistor connected

to the base of the transistor is

referred to as

[ a]a) Darlington pairb) CE &CC cascade

c) cascade amplifier

d) differential pair

ans: [ A ]

33) o/p voltage of an ideal differential amplifier

[ b ]

a) zero

b) Ad Vdc)Ad Vd + AcVc

d) AcVcans:[ B ]

34) bandwidth of an amplifier with lower & higher cutoff frequency F l & Fh .& quantity factor Q

is [ a ]


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a) Fh - F lb) Fh/ q

c) (Fh-Fl)/1.414

d) q-Flans: [ A ]

35) identify the expression for voltage gain CD & fet amplifier at low frequency

[ b ]

a) -gm rd Rl /(rd + Rl)

b) gm rd Rl / ( rd +Rl+ gm rd Rl)

c) gm rd Rl /(rd + Rl)

d) Rl || rd / (1+ gm rd)

ans: [ B ]

36) the i/p impedance of cascade amplifier is

[ b ]

a) hic

b) hie

c) infinity

d) hib

ans: [ B ]

37) the transconductance gm of a transistor depend on[ b ]

a) temperature

b) operation frequencyc) CE voltage

d) C cans : [ B ]

38) ft for a ce amplifier is defined as

[ b ]

a) the frequency at which the CE current gain falls to half its Max value

b) frequency at which CE current gain becomes unityc) frequency at which CE voltage gain falls to half its Max value

d) frequency at which CE voltage gain becomes unity

ans: [ B ]


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39) the capacitance determining the corner frequency lag network at the i/p of CE amplifier is

[ b ]

a) miller i/p capacitorb) c wiringc) external capacitor at the base

d)cbe

ans: [ B ]

40) i/p signals swing in class A power amplifier is restricted to

[ d ]

a) a small portion around Q point in active region

b) entire portion around Q point in saturation

c) entire portion around Q point in cutoff

d) entire portion around Q point in active

ans: [ D ]

41) transistor in class C amplifier is based beyond cutoff region to

[ b ]

a) ensure reduced distortion of o/p signal

b) ensure conduction angle of less than 1800c) ensure conduction angle of transistor for entire i/p cycle

d) ensure o/p wave shape to the replica of i/p wave shapeans: [ B ]

42) if Av is the voltage gain of an amplifier in db & Ai is its current gain in db then power gain of

amplifier in db is [ d ]

a) Av- Ai

b) Av/ Ai

c)10log 10 Av/ Ai

d) Av+Aians : [ D ]

43) at frequency below lower cut off frequency in CE amplifier coupling capacitor at the base of

the amplifier form an LPF [ b ]

a) with emitter resistance

b) with i/p resistancec) with o/p resistance


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d) with base resistance

ans: [ B ]

44) advantage of impedance type inter stage coupling is[ c ]

a) very wide band & frequency independent gain curve

b) flat response of frequency in mid band region

c) no dc voltage drop across collector loadd) no requirement of bulky components all frequency

ans: [ C ]

45) resultant phase shift of odd number of CE amplifier stages at mid band frequency is

[ b ]

a) 3600

b)1800c) 450

d) 900

ans: [ B ]

46) major draw back of Darlington transistor pair

[ d ]

a) low current gain compared to single emitter follower

b) dependence of Av on transistor selected

c) low i/p impedance compared to single emitter follower

d) dependence of H -parameters on quiescent conditionsans: [ D ]

47) lower cutoff & higher cut off frequency of an rc coupled amplifier are

[ c ]

a) both zero

b) both infinityc) similar to of CE stage

d) zero& infinity

ans: [ C ]

48) main characteristic features of differential amplifier is absence of frequency dependent

components


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49) identify the incorrect statement for a Hybrid pie model of a BJT

[ b ]

a) base width modulation due to earlier effect results in variations in collector emitter

voltages

b)Hybrid pie model cannot be used for analysis of transistors at high frequencies

c) High frequency hybrid pie conductance can be expressed in terms of low frequency H

parameters

d) All the conductances & capacitances of Hybrid pie model are independent of operating

frequencies

Ans: [ b ]

50) Frequency of Fbeta = a product of current gain & band width of CE amplifier

51) The miller i/p capacitance in CB amplifier

[ c ]

a) Is large compared to miller capacitance in CE

b) is very large because of +ve voltage gain in CB

c) is small because of +ve voltage gain in CBd) not negligible compared to other capacitance

ans: [ C ]

52) in class A amplifier flow of electric current in terms of i/p signal cycle is for 3600

53) an ideal voltage will have effective o/p impedance =

[ b ]

a) no particular value

b)zeroc) always a complex value

d) infinity

ans: [ B ]

54) type of inter stage coupling resulting in highest overall gain[ c ]

a) direct coupling

b)inductive coupling

c) RC couplingd) transistor coupling

ans : [ C ]


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55) main disadvantage of Darlington pair amplifier is

[ d ]

a) low i/p impedanceb) low current gain

c) high o/p impedance

d)high leakage current

ans: [ D ]

56) ideal value of CMRR of differential amplifier is

[ d ]

a) unity

b) zero

c)100

d) infinity

ans: [ D ]

57) CE is the capacitance of forward biased junction & is therefore

[ c ]

a) independent of collector current

b) much lager than Cc

c) mainly diffusion capacitance

d) mainly transition capacitanceans: [ C ]

58) dissipation capability of a transistor is defined as

[ a ]

a) capability to launch heat generated into the surroundingsb) deviation in power delivered to load resistor

c) capability to withstand the variation in dc power at operating power

d) deviation in o/p & i/p signal wave shapes

ans: [ A ]

59) increased conversion efficiency in class B over class A operation is mainly due to

[ b ]

a) elimination of all higher harmonics

b) elimination of dc current in the load

c) usage of single power supply

d) elimination of cross over distortion


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ans: [ B ]

60) higher cutoff frequency of transistor amplifier is mainly because of[ a ]

a) inter electrode capacitance

b) bypass capacitance

c) blocking capacitance

d ) coupling capacitance

ans: [ A ]

61) phase difference between o/p voltage &i/p voltage of a CC amplifier at mid band frequencies

[ b ]

a) 1800

b) 00c) 450

d) 900

ans : [ B ]

62) phase difference between o/p voltage &i/p voltage of a CG amplifier at mid band frequencies

[ b ]

a) 1800b) 00c) 450

d) 900

ans : [ B ]

63) audio power amplifiers are also generally referred to as large signal amplifiers

64) ratio of slopes of the gain curve of an amplifier below lower cutoff frequency & above cutoff

frequency is [ b ]

a) 3b) unity

c)2

d) 6

ans: [ B ]

65) the capacitors that are short circuited at low frequencies in CE amplifier are

[ d ]


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a) o/p coupling capacitors

b) i/p coupling capacitors

c) emitter bypass capacitorsd) inter electrode capacitor

ans:[ B ]

66) the critical capacitance that determines the overall cut off frequency of an amplifier is the

one which sees an equivalent resistance [ a ]

a) of minimum value

b) of Max value

c) of infinity value

d) equals to its reactance value at that frequency

ans: [ A ]

67) distortion in amplifiers due to unequal amplitude gains at different frequencies is referred to

as [ c ]

a) phase shift distortion

b) amplitude distortion

c) frequency distortiond) delay distortion

ans : [ C ]

68) slope of the gain curve of an amplifier below cut off frequency is

[ a ]

a) -20 db decadeb) 6 db decade

c)-6 db decade

d) 20 db decade

ans : [ A ]

69) the CE short circuit current gain in db at frequency f = Ft is

[ d ]

a) hfe/1.414

b) unity

c) hfe

d)zero

ans: [ D ]


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70. The frequency at which CE is short circuit current gain becomes unity is represented

by__fT_______

71. Non linear distortion is maximum ina) Class B mode a) Class A mode

a) Class AB mode d) a) Class C mode

Ans: (b)

72. Even harmonics are not present in the o/p of Class B push pull amplifier.

73. Phase difference between o/p and i/p voltages of a transistor amplifier at lower cut off

frequencies is

a)180 b) 45 c) 0 d) 90

Ans: (b)

74. All frequencies below lower cut off frequency in a CE amplifier, the coupling capacitor at the

base of the amplifier forms a LPF

a)with RE b)Rip c)RB d)RopAns: (b)

75. A CC amplifier is characterized by approximately

A)unity power gain b)unity i/p ,o/p impedance ratio

c)unity voltage gain d) unity current gain

Ans: (c)

76. Voltage gain

of a given CS FET depends on its

a)Dynamic drain resistance b)i/p impedance

c) Amplification factor d)Drain load resistance

Ans: (d)

77. Identify the expression for o/p resistance of a CE amplifier at lower frequencies is

Ans: 1/[ho-hrhf/hi+rs]

78. The type of inter stage coupling used at extremely low frequencies is

a)Inductive coupling b)RC couplingc) Transformer coupling d) Direct coupling

Ans: (d)

79. Resultant phase shift of even no of CG amplifier stages at higher cut off frequencies is

Ans: Sum of phase shift introduced by individual stages.


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80. According to Millers theorem, inter electrode capacitances Ccb for a CE amplifier of gain A

results in an miller i/p capacitance of

a) Ccb (A-1)/A b) CcbA/ (A-1)

c) Ccb (1-A) d) Ccb / (A-1)Ans: (a)

81. A two transistor combination in CE, CC is not characterized by

a)AI1 c) a)AV> fhout b) fhin


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dynamic curve of the active device is referred to as

(a) amplitude distortion (b) frequency distortion

(c) phase shift distortion (d) delay distortionAns: (D)

90) Differential voltage gain Ad of a difference amplifier with a voltage gain of individual

amplifier circuit A1 and A2

(a) A1-A2 (b) (A1+A2)/2

(c) (A1-A2)/2 (d) A1+A2

Ans: (c)

91) Cc is the capacitance of the reverse biased collector base junction and is therefore

(a) Independent of collector current(b) mainly transistor capacitance

(c) much larger than Ce(d) mainly diffusion capacitance

Ans: (b)

92) Cross over distortion in class B amplifier is due to

(a) finite cut-off voltage of the two transistors

(b) non-identical behaviour of the two transistors

(c) elimination of two power supplies in the circuit

(d) elimination of even harmonics in the o/p

impedanceAns: (a)

93) Large i/p impedance and small o/p impedance are possible in

Ans) common collector amplifier

94) Identify the correct statement with reference to class B amplifier

Ans) Even harmonics are cancelled in the

95) CE amplifier is characterized by

Ans) moderate i/p impedance

96) Phase relationship between o/p and i/p voltage of a CS amplifier for frequency below lowercut-off frequency is

(a) both are in phase(b) o/p lags i/p(c) output leads i/p(d) both are 180 out of phase

Ans: (c)

97) Identify correct statements


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Ans) Gain and Bandwidth change such that product is same

98) Cascading of two identical amplifiers with individual gains of 100results in

Ans) overall gain of 8db

99) Resultant phase shift of 6 common source amplifier stages cascaded at mid band frequency is

Ans) 180

100) Major advantage of boot strap Darlington pair over single Darlington pair is

(a) High overall Av with proper DC biasing(b) increased Ai irrespective of bias condition(c) high i/p impedance irrespective of bias condition(d) increased Ai depending upon the bias conditionAns: (c)

101) The frequency up to which hybrid model is valid is

(a) 3ft (b) 2ft (c) ft/3 (d) ft/2

Ans: (c)

102) Identify correct statement in the following statements

(a) for wide brand operation RL 2k(b) the band width of CE amplifier is dependent on the load resistance RL(c) At high frequency o/p conductance are generally negligible compared to RL(d) For wide band operation RL >>2k

Ans: (a)

103) The location of operation point of a class A amplifier is

Ans) active region

104) Total harmonic distortion is maximum in

Ans) class C

105) Effect of small value of unbiased emitter resistance in CE amplifier is

(a) Increase in voltage gain at mid band frequency(b) Decrease in Av at high frequency(c) Nothing on voltage gain at mid band frequency(d) Decrease in Av at mid band frequency

Ans: (d)

106) The mid band gain of BJT is 200 and its bandwidth is 1MHz .If circuit parameters are

changed such that the gain reduces to 10,the bandwidth coil


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(a) remains same (c) also reduces to 1/10th

(c) increases to 20MHz (d) increases to 10 MHz

Ans: (c)

107) Resultant phase shift of five CE emitter amplifier stages cascaded at mid band frequencies

is

(a) 360 (b) 180 (c) 45 (d)90Ans: (b)

108) Typical value of gm of Ge BJT at room temperature and Ic=1.3mA is

(a) 50mA/volt (b) 1000 (c) 80k (d) 4MAns: (a)

109) [hie gm/hfe] represent hybrid conductance

(a) Feed back conductance gbc(b) Base spreading conductance gbb

(c) o/p conductance gce(d) i/p conductance gbc

Ans: (b)

110) Frequency response of an amplifier is defined as

(a) variation of amplifier frequency as a functionof its voltage gain

(b) variation of magnitude of voltage gain as a

function of phase of the voltage gain

(c) variation of magnitude and phase of voltage

gain with variation in signal frequencies

(d)variation of amplifier frequency as a function of the phase of its voltage gain

Ans: (c)

111) Critical capacitance along the smallest equivalent resistance that determines the lower

cut-off frequency of a common drain amplitude is

(a) C1,input coupling capacitor(b) Cs,source by pass capacitor(c) Cs,source by pass capacitor ,only if C1=C2(d) C2,output coupling capacitor


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Ans: (d)

112) Resultant upper-cut-off frequency of two identical stages cascaded with individual upper

cut-off frequency of 10 KHz is

(a) 6.4 KHz (b) 15.625KHz (c) 10 KHz (d) 5 KHz

Ans: (a)

113) In a two stage BJT cascade amplifier

(a) I/P resistance is comparable with hie of a singleCE stage

(b) O/P resistance is as low as hoe of a single CEStage

(c) Reverse voltage gain is much larger than hre of a

Single CE stage

(d) Forward current gain is much smaller than hfe ofSingle CE stage

Ans: (c)

114) Typical value of rbc of Ge BJT at room temper--ture and Ic=1.3mA is

(a) 1000 (b) 4M (c) 100 (d) 80KAns: ( b)

115) Identify the conductance that is not included in hybrid - model(a) Base emitter conductance, gbe(b) O/P conductance, gce

(c) Feed back conductance,gbc(d) I/P conductance, gbc

Ans: (a)

116) Class C amplifier find applications in the

following

(a) amp modulation circuits(b) driving loud speakers(c) switching devices(d) comparators

Ans: (a)

117) Mid frequency amplifier range of an amplifier is defined as those frequencies more than 10

times that of lower frequencies and less than 0.1 times that of higher frequency in amplifier does

not have any mid frequency range if


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(a) fH100fL

Ans: (a)

118) The mid band voltage gain of an amplifier with band width of 1MHz is 10db,if the circuitcomponents are changed such that the gain becomes 7db ,its bandwidth becomes

(a) 700 KHz (b) 2 MHz (c) 500 KHz (d) 1 MHz

Ans: (b)

119) Resultant voltage gain and phase shift in an n-stage cascaded amplifier with individual

gains, A1, A2, A3 An and phase shifts 1, 2 n is(a) Ar=A1.A2.A3..An and =1+2+. +n

(b) Ar=A1.A2An and =1.2n(c) Ar=A1+A2++An and =1.2..n(d) Ar=A1+A2+.+An and =1+2+.+n

Ans: (a)

120) Break frequency is the frequency at which the capacitive reactance (Xc) and equivalent

resistance (Req) at a point of connection in a circuit have following relation

(a) XcReqAns: (c)

121) Basic advantage of DC of amplifier stage is

(a) Ability to provide impedance matching(b) Ability to provide very small mid band region(c) Ability to provide narrow and resonant type of frequency response(d) Ability to amplify DC and very low frequency signal

Ans: (d)

122) Two stage common emitter amplifier configuration with emitters tied together, i/ps at basesand o/ps at collectors is called as

(a) Differential pair (b) Cascode amplifier

(c) Boot strap Darlington pair (d) Darlington pair

Ans: (a)

123) Effect of resistor N/W for biasing the

Darlington resistor

Ans) Reduction in overall I/P impedance

124) If a power transistor conducts only during +ve half cycle of i/p signal , the class of operation

of the amplifiers is

Ans) Class B


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125) Max conversion efficiency of a Class B power amplifier is

Ans) 78.5%

126) If the signal voltages and currents at the i/p of a transistor amplifier are within 1/10 th of DC

operating point values then transistor is said to be in

(a) small signal mode(b) low frequency mode(c) frequency independent mode(d) DC operating mode

Ans: (a)

127) Phase reversal between O/P and I/P voltages in a CE amplifier occurs at

(a) mid band frequency (b) high cut off frequency

(c) all the frequency (d) lower cut off frequency

Ans: (a)

128) Resonant peak in the frequency response occurs in

(a) DC coupling (b) RC coupling

(c) direct coupling (d) Transformer coupling

Ans: (d)

129. If 2 signals of some amplitude and frequency are applied to a differential amplifier theoutput is mainly due to the phase difference between the input signals

130. The output conductance gbe in terms of low frequency h parameter is given by D/ hfe Re .

131. If power transistor conducts for the entire cycle of input signal , the mode of power amplifier

is Class A.

132. Identify the incorrect statement with reference to Class B amplifier

Ans: A phase inversion is not required at input in Push Pull Amplifier.

133. Doubling the voltage gain of an amplifier results in increase of voltage gain in dB by3.01.

134. To obtain a constant and high value of voltage gain at midband frequency in CE Amplifier

CEshould be large enough such that Xce


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136. Cross over distortion in Class B amplifier is due to finite cut-in voltage of 2 transistors.

137. If there are 2 uncoupled high pass filter sections in the equivalent circuit of an amplifier

with fL1 and fL2 as cutoff frequency , then the overall lower cutoff frequency of the amplifierapproximately is

a) fL2 - fL1b) smaller of fL2 and fL1

c) fL2 + fL1

d) Larger of fL2 and fL1 , if fL2 and fL1 differ by more than a decade.Ans: (d)

138. The phase relationship between output and input voltages of a CS amplifier for frequency

above higher cut off frequency is

a) both are 180 degrees out of phase

b) output leads input

c) both are in phase

d) output lags inputAns: (d)

139. According to Millers theorem , the inter-electrode capacitance, Ccb for a CE amplifier of gain

A results in a Miller output capacitance of

a) Ccb(A-1)/A b) Ccb A/(A-1) c) Ccb(1-A) d) Ccb/(A-1)

Ans: (a)

140. If V1 = -V2 = 0.5 V are the two input signals applied to a differential amplifier , identify theincorrect statement

a) Common mode voltage is 0

b) Differential mode voltage is 1V

c) Differential mode voltage is 0d) Output voltage = Differential mode gain

Ans: (c)

141. Gain in dB as a negative number indicates

a) an absolute gain less than 20

b) an absolute gain less than 1

c) an absolute gain less than 0d) Phase reversal between i/p and o/p

Ans:

142. Crossover distortion in Class B amplifiers can be eliminated by modifying the configuration

to Class AB .

143. A voltage gain equal to 0dB of an amplifier corresponds to


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a) Power gain of 2

b) Voltage gain of 2

c) Voltage gain of unity

d) Power gain of zero

144. Configuration of transistor amplifier that acts as a buffer for impedance matching is

145. Resultant lower and upper cut off frequency f1n and f2n of an n stage cascaded identical

amplifier is

146. A cascade amplifier is a combination of

147. Typical value of Cc of high frequency hybrid model of a BJT is

148. Resultant upper 3dB frequency of n identical upper cut off frequency given asa) ( f2 )n

b) f2(21/n-1)c) f2 /(21/n-1)d) f2

Ans:

149. Base width modulation due to early effect results in variations in collector emitter

voltages

150. Input impedance is high and output impedance is low in the following transistor

configurationsa) CC b) CB c) CC and CB d) CE

Ans:

151. Identify the correct statement

a) Change in bandwidth for any change in its gain is always 3dB

b) If the gain of an amplifier decreases by 3 dB , its bandwidth remains the same.

c) Gain and bandwidth of an amplifier change such that their product always remainsthe same.

d) If the gain of an amplifier increases by 3 dB its bandwidth also increases by 3 dB

Ans: (c)

152. Class of operation of power amplifier with transistor conduction for a period much smaller

than half cycle input signal is Class C.

153. Class C amplifiers are used as Tuned amplifiers.


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