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EDC
UNIT-2
1) If a resistor is introduced in the emitter of a common-emitter(CE)
amplifier then
(A) both input impedance and voltage gain increases
B) input impedances increases and voltage gain decreases
(C) input impedances decreases and voltage gain increases
(D) both input impedances and voltage gain decreases
Ans. B
Current stability of a CC amplifier can be increased by
2)
A) Reducing both emitter and base resistance
B) Increasing both emitter and base resistance
C) Reducing emitter resistance and increasing base resistance
D) Increasing emitter resistance and decreasing base resistance
Ans. A
3) Which of the following statements are correct for basic transistor
amplifier configuration?
A) CB amplifier has low input impedance and a low current gain
B) CC amplifier has low output impedance and a low current gain
C) CE amplifier has very poor voltage gain but very high input impedance
D) The current gain of CB amplifier is higher than the current gain of CC
amplifier
Ans. A
4)
In the BJT amplifier, the transistor is biased in the forward active
region putting a capacitor across RE will:
A) Decrease the voltage gain and decrease the input
impedance
B) Increase the voltage gain and decrease the input
impedance
C) Decrease the voltage gain and increase the input
impedance
D) Increase the voltage gain and increase the input
impedance
Ans. C
5)
In a common emitter BJT amplifier, the maximum usable supply
voltage is limited by:
A) Avalanche breakdown of base–emitter junction
B) Collector–base breakdown voltage with emitter open
(BVCBO)
C) Collector–emitter breakdown voltage with base open
(BVCEO)
D) Zener breakdown voltage of the emitter -base junction
Ans. B)
6)
Introducing a resistor in the emitter of a common emitter amplifier
stabilizes the dc operating point against variations in:
A) Only the temperature
B) Only the β of the transistor
C) Both temperature and β
D) None of the above
Ans.C
7)
In a CE transistor amplifier, if collector–emitter voltage increases
the instantaneous operating point:
A) Moves up the load line
B) Moves down the load line
C) Moves at right angle to the load line
D) Remains stationary
Ans. A
8)
The h-parameter equivalent circuit of a junction transistor is valid
for:
A) High frequency, large signal operation
B) High frequency, small signal operation
C) Low frequency, small signal operation
D) Low frequency, large signal operation
Ans. C
9)
The small signal input impedance of a transistor when the output
is shorted for the measuring signal, is: (where the symbols have
then usual measuring)
Ans. A
For obtaining hybrid parameters of a transistor:
10)
A) Variable Vbe and Ie are taken as independent variables
B) The two independent variables are the ones that are most easily
measurable for a CE configuration
C) Variable ib and vce ie are taken as dependent variables
D) Variable Vbe and ie are taken as dependent variables
Ans: C
The condition necessary to calculate hoe of a transistor:
11)
A) DC base current is to be zero
B) Base to emitter voltage is to be constant
C) Collector current is to be constant
D) Base current is to be constant
Ans. D
12) The approximate value of input impedance of a common emitter
1amplifier with emitter resistance Re is given by:
6
)
A)hie + A1Re
B)hie + (1 + hfe) Re
C)hie
D)(1 + hfe) Re
Ans.B
13) Which of the following configurations has the lowest output impedance?
A.Fixed-bias
B. Voltage-divider
C. Emitter-follower
D.None of the above
Ans. C
14) Which of the h-parameters corresponds to hre in a common-base
configuration?
A.hib
B. hfb
C. hrb
D.hob
Ans. C
15) Refer to this figure. Find the value of IE.
A.2 mA
B. 4 mA
C. 5 mA
D.6 mA
16) Which of the following is referred to as the reverse transfer voltage
ratio?
A.hi
C. hf
B. hr
D.ho
Ans. B
17) Which of the following conditions must be met to allow the use of the
approximate approach in a voltage-divider bias configuration?
A. re > 10R2
B. RE > 10R2
C. RE < 10R2
D. re < 10R2
Ans. B
18) Refer to this figure. Determine the value of Av.
A.49.6
B. 5
C. 100
D.595
Ans. A
19)
For a common-emitter amplifier, the purpose of swamping is
A.to minimize gain.
B. to reduce the effects of r'e
C. to maximize gain.
D.no purpose.
Ans. C
20) What is the typical value of the current gain of a common-base
configuration?
A.Less than 1
B. Between 1 and 50
C. Between 100 and 200
D.Undefined
Ans. A
21) What is the most important r parameter for amplifier analysis?
A.rb′
B.rc′
C. re′
Ans. C
22) The ________ model fails to account for the output impedance level of the
device and the feedback effect from output to input.
A.hybrid equivalent
B. re
C.
D.Thevenin
Ans. C
23)
Refer to this figure. Calculate the value of VB.
A.5 V
B. 3.7 V
C.20 V
D.3 V
Ans. B
24) You have a need to apply an amplifier with a very high power gain. Which
of the following would you choose?
A.common-collector
B. common-base
C. common-emitter
Ans. C
D.emitter-follower
25) What is the voltage gain of a feedback pair connection?
A.1
B. –1
C. 100
D.–100
Ans. A
26)
A common-emitter amplifier has ________ voltage gain, ________
current gain, ________ power gain, and ________ input impedance.
A.high, low, high, low
B. high, high, high, low
C. high, high, high, high
low, low, low, high
D
Ans. C
27) What is the range of the input impedance of a common-base
configuration?
A.A few ohms to a maximum of 50
B. 1 k to 5 k
C. 100 k to 500 k
D.1 M to 2 M
Ans. C
28)
What is the typical range of the output impedance of a common-emitter
configuration?
A.10 to 100
B. 1 k to 5 k
C. 40 k to 50 k
D.500 k to 1 M
Ans. B
29)
What is the unit of the parameter ho?
A.Volt
B. Ohm
C. Siemen
D.No unit
Ans. C
30)
Refer to this figure. Calculate the value of Rin(tot).
A.37.7 k
B. 3.77 k
C. 378
D.2.25 k
Ans. B
31) What is the range of the current gain for BJT transistor amplifiers?
A.less than 1
B. 1 to 100
C. above 100
All of the above
D.
Ans. D
32) What does the negative sign in the voltage gain of the common-emitter
fixed-bias configuration indicate?
A.The output and input voltages are 180º out of phase.
B. Gain is smaller than 1.
C. Gain is larger than 1.
D.None of the above
Ans. A
33) For the common-emitter fixed-bias configuration, there is a ________
phase shift between the input and output signals.
A.0º
B. 45º
C. 90º
D.180º
Ans. D
34) Which one of the following configurations has the lowest input
impedance?
A.Fixed-bias
B. Common-base
C. Emitter-follower
D.Voltage-divider?
Ans. B
35) The differential amplifier has
A.one input and one output.
B. two inputs and two outputs.
C. two inputs and one output.
D.one input and two outputs.
Ans. C
36) The emitter-follower configuration has a ________ impedance at the
input and a ________ impedance at the output.
A.low, low
B. low, high
C. high, low
D.high, high
Ans. C
37)
The differential amplifier produces outputs that are
A.common mode.
B. in-phase with the input voltages.
C. the sum of the two input voltages.
D.the difference of the two input voltages.
Ans. D
38) The ________ model suffers from being limited to a particular set of
operating conditions if it is to be considered accurate.
A.hybrid equivalent
B. re
C.
D.Thevenin
Ans. A
39) The ________ configuration is frequently used for impedance matching.
A.fixed-bias
B. voltage-divider bias
C. emitter-follower
D.collector feedback
Ans. C
40)
Refer to this figure. You notice while servicing this amplifier that the
output signal at Vout is reduced from normal. The problem could be
caused by
A.an open C3.
B. an open C2.
C. an open base-emitter of Q2.
D.a shorted C2.
Ans. B
41)
When the bypass capacitor is removed from a common-emitter
amplifier, the voltage gain
A.increases.
B. decreases.
C. has very little effect.
D. None of the above
Ans.B
52) Refer to this figure. Determine the value of VC.
A.20 V
B. 10 V
C. 5 V
D.0 V
Ans. c
53). In a common-base amplifier, the input signal is connected to the
A.base.
B. collector.
C. emitter.
D.output.
Ans. C
54)
Which of the following is (are) true to achieve a good overall voltage
gain for the circuit?
A.The effect of Rs and RL must be considered as a product.
The effect of Rs and RL must be considered as a product and evaluated
B.
individually.
C. The effect of Rs and RL must be evaluated individually.
D.None of the above
Ans. B
55)
To analyze the common-emitter amplifier, what must be done to
determine the dc equivalent circuit?
A.leave circuit unchanged
B. replace coupling and bypass capacitors with opens
C. replace coupling and bypass capacitors with shorts
D.replace VCC with ground
Ans. B
56)
For the common-emitter amplifier ac equivalent circuit, all capacitors
are
A.effectively shorts.
B. effectively open circuits.
C. not connected to ground.
D.connected to ground.
Ans. A
58)
Under which of the following conditions is the output impedance of the
network approximately equal to RC for a common-emitter fixed-bias
configuration?
A.ro 10RC
B. ro < 10RC
C. ro < ro
D.ro > ro
Ans. A
59). Which of the following gains is less than 1 for a common-base
configuration?
A.Ai
B. Av
C. Ap
D.None of the above
Ans. A
60) Which of the following define(s) the conversion efficiency?
A.Ac power to the load/ac input power
B. Ac power to the load/dc power supplied
C. Dc output power/ac input power
D.All of the above
Ans. D
61)
Which of the following should be done to obtain the ac equivalent of a
network?
A.Set all dc sources to zero
B. Replace all capacitors by a short-circuit equivalent.
C. Remove all elements bypassed by the short-circuit equivalent.
D All of the above
Ans. D
62) In an unbypassed emitter bias configuration hie replaces
________ in the re model.
A.re
B.
C. re
D.Ib
Ans. C
63)
Which of the following is (are) true regarding the input
impedance for frequencies in the midrange 100 kHz of a BJT
transistor amplifier?
A.The input impedance is purely resistive.
B. It varies from a few ohms to megohms.
An ohmmeter cannot be used to measure the small-signal ac
C.
input impedance.
D.All of the above
Ans. D
64)
For the collector dc feedback configuration, there is a
________ phase shift between the input and output signals.
A.0º
B. 45º
C. 90º
D.180º
Ans. D
65)
A common-collector amplifier has ________ input resistance,
________ current gain, and ________ voltage gain.
A.high, high, low
B. high, low, low
C. high, low, high
Ans. A
66)
The total gain of a multistage amplifier is the ________.
A.sum of individual voltage gains
B. sum of dB voltage gains
Ans. B
67) Which of the following configurations has an output impedance Zo
equal to RC?
A.Fixed-bias common-emitter
B. Common-emitter voltage-divider with bypass capacitor
C. Common-emitter voltage-divider without bypass capacitor
D.All of the above
Ans. D
69). For a common-emitter amplifier, the purpose of the emitter bypass
capacitor is
A.no purpose, since it is shorted out by RE.
B. to reduce noise.
C. to despike the supply voltage.
D.to maximize amplifier gain.
Ans. D
70) For BJT amplifiers, the ________ gain typically ranges from a level just
less than 1 to a level that may exceed 1000.
A.Voltage
B. Current
C. Impedance
D.All of the above
Ans. B
71) Which of the following configurations has a voltage gain of –RC /re?
A.Fixed-bias common-emitter
B. Common-emitter voltage-divider with bypass capacitor
C. Fixed-bias common-emitter and voltage-divider with bypass capacitor
D.Common-emitter voltage-divider without bypass capacitor
Ans. D
72) An emitter-follower amplifier has an input impedance of 107 k . The
input signal is 12 mV. The approximate output voltage is (commoncollector)
A.8.92 V
B. 112 mV
C. 12 mV
D.8.9 mV
Ans. C
73)
Refer to this figure. The output signal from the first stage of this
amplifier is 0 V. The trouble could be caused by
A.an open C4.
B. an open C2.
C. an open base-emitter of Q1.
D.a shorted C4.
Ans C
74) What is the limit of the efficiency defined by = Po / Pi?
A.Greater than 1
B. Less than 1
C. Always 1
D.None of the above
Ans. B
75) What is Beta equal to in terms of h parameters?
A.hre
B. hoe
C. hie
D hfe
Ans. D
76) What is the controlling current in a common-base configuration?
A.Ie
B. Ic
C. Ib
D.None of the above
Ans. A
77)
Which of the following techniques can be used in the sinusoidal ac
analysis of transistor networks?
A.Small-signal
B. Large-signal
C. Small- or large-signal
D.None of the above
Ans. A
78) The input impedance of a BJT amplifier is purely ________ in nature and
can vary from a few ________ to ________.
A.resistive, ohms, megohms
B. capacitive, microfarads, farads
C. inductive, millihenrys, henrys
D.None of the above
Ans. A
79) The ________ the source resistance and/or ________ the load resistance,
the less the overall gain of an amplifier.
A.smaller, smaller
B. smaller, larger
C. larger, smaller
D.larger, larger
Ans. C
80) Refer to this figure. If an emitter bypass capacitor was installed, what
would the new Av be?
A.4.96
C. 398
B. 125
D.600
Ans. B
81) Which of the following statements is true for hybrid model and re model
for a transistor amplifier?
(A) re model is limited to a particular set of operating conditions while hybrid
model works for the whole region of operation.
(B) Hybrid model is limited to a particular set of operating conditions while re
model works for the whole region of operation.
(C) Both models are exactly the same.
(D) None of the above.
Ans. C
82) While drawing the ac equivalent model for a BJT amplifier,
(A) All the capacitors and DC sources are open circuited.
(B) All the capacitors and DC sources are short circuited.
(C) Capacitors are short circuited and DC sources are open circuited.
(D) Capacitors are open circuited and DC sources are short circuited.
Ans. B
83) For an ac equivalent model of CE Fixed Bias configuration
(A) Input and output impedances are approximately equal.
(B) Input Impedance is large as compared to the output impedance.
(C) Input impedance is small as compared to the output impedance.
(D) None of the above.
Ans. B
84) For ac equivalent models of CE Fixed bias and CE voltage divider bias,
reducing ro?
(A) Causes an increase in Zo, Av and Ai.
(B) Causes a decrease in Zo, Av and Ai.
(C) Has no effect on Zo, Av and Ai.
(D) None of the above.
Ans. B
85) To isolate the dc analysis from the ac analysis of transistor small signal
amplifier
(A) Superposition theorem is used because transistor small signal amplifiers are
considered non- linear.
(B) Superposition theorem is used because transistor small signal amplifiers are
considered linear.
(C) None of the above.
Ans. B
86) The ideal maximum voltage gain of a common-collector amplifier is what?
(A) infinite
(B) zero
(C)indeterminate
(D)1
Ans. D
87) What happens to the gain of an amplifier if negative feedback is added?
(A) increases
(B)decreases
© becomes zero
(D) becomes infinite
Ans. B
88)A common collector amplifier is best described by which of these?
(A) low voltage gain
(B) high voltage gain
© low input resistance
(D) low current gain
Ans. A
89) What coupling is used in a multi-stage amplifier for amplifying DC
signals?
(A) direct
(B) RC
C) R
(D) transformer
Ans. A
90) Which configuration gives the highest power gain?
(A) common-base
(B) common-emitter
C) Common-collector
(D) common-ground
Ans. B
91) Which of the following is not a BJT amplifier configuration?
(A) common-base
(B) common-source
C) common-emitter
(D) common-collector
Ans. B
92) The point of intersection of the DC and AC load lines is called what?
(A) cut-off point
(B) saturation point
(C operating point
(D) common point
Ans. C
93) Compared to the CE and CC amplifier, a CB amplifier exhibits which of
the following?
(A) lower input resistance
(B) larger voltage gain
©larger current gain
(D) higher input resistance
Ans. A
94) What load does a transistor see at zero signal condition?
(A) AC
(B)DC
C) AC and DC
(D) Zero
Ans. D
95) In the AC equivalent of a transistor amplifier, capacitors are considered
as what?
(A) short
(B) open
(C resistive
(D) power supply
Ans. A
96) What is another name for a common-emitter circuit?
A) Grounded emitter
B) Grounded base
C) Grounded collector
D) Emitter-follower
Ans. A
97) A CE amplifier always exhibits what output signal?
A) Equal to the input signal
B) Greater than the input signal
C) out of phase with the input signal
D) In phase with the input signal
Ans. C
98) Which of the following is an emitter follower circuit?
A) common base amplifier
B) common emitter amplifier
c) common collector amplifier
D) differential amplifier
Ans. C
99) A buffer amplifier helps achieve which of the following?
A) minimum loading and maximum mismatch
B) minimum loading and minimum mismatch
C) maximum loading and minimum mismatch
D) maximum loading and maximum mismatch
Ans. B
100) An emitter follower is often used for what?
A) impedance matching
B) voltage amplification
C) current amplification
D) power amplification
Ans. A
101) Why must the impedance of the load match the impedance of the
amplifier?
A) to minimize power transfer
B) to prevent signal distortion
C) to maximize signal to noise ratio
D) to maximize power transfer
Ans. D
102) What is the main benefit of cascading amplifiers?
A) lower power supply
B) lesser distortion
C) longer amplifier life
D) higher over-all gain
Ans. D
103) Which of the following has an input impedance that depends strongly on
load resistance?
A) CB
B) CE
C) CC
D) CD
Ans. B
104) Which transistor mode gives the inverted output: A) Common Emitter
B) Common Base
C) Common Collector
D) None of these
Ans. A
105) Which coupling gives the higher gain in case of amplifier: A) Capacitor coupling
B) Impedance coupling
C) Transformer coupling
Ans. A
106) The important characteristic of emitter-follower is
(A) high input impedance and high output impedance
(B) high input impedance and low output impedance
(C) low input impedance and low output impedance
(D) low input impedance and high output impedance
Ans. B
107) The common collector amplifier is also known as
(A) collector follower
(B) Base follower
(C) Emitter follower
(D) Source follower
Ans: C
108) In class–A amplifier, the output current flows for
(A) a part of the cycle or the input signal.
(B) the full cycle of the input signal.
(C) half the cycle of the input signal.
(D) 3/4th of the cycle of the input signal.
Ans.:- B
109) In an amplifier with negative feedback
(A) only the gain of the amplifier is affected
(B) only the gain and bandwidth of the amplifier are affected
(C) only the input and output impedances are affected
(D) All of the four parameters mentioned above would be affected
Ans.:- D
110) If the Q of a single-stage single-turned amplifier is doubled, then its
bandwidth will
(A) remain same
(B) become half
(C) become double
(D) become four times
Ans. B