ECA
JNTUH OBJECTIVE EXAM
UNIT-1: (SINGLE STAGE
AMPLIFIERS)
SECTION-I : Choose the
correct answers
1. Which of
the following amplifier has high power gain [ b]
(a) CB (b) CE (c) CC (d) both CB and CE
2. The slope
of ac load line is _________ that of dc load line. [b ]
(a) same as (b)more than (c) less than (d) None of
the above
3. In a RC
coupled amplifier, which of the following component is mainly responsible for
harmonic distortion of the signal [ a]
(a) Transistor (b) Biasing resistor (c) coupling
capacitor (d) power supply
4. The voltage
gain of well designed single stage CB amplifier is essentially determined by ac
collector load and [C ]
A. Emitter resistor Re B. ac alpha C. Input
resistance emitter diode D.ac beta.
5. The emitter
of a CE amplifier has no AC voltage because of the [c ]
A. DC voltage unit B. Bypass Capacitor C. Coupling capacitor
D. load resistance
6. Typical
value of hie
is [ ]
A. 1k B. 25k C.50k D.100k
SECTION-II: Fill in the
blanks
7. The parameter h22 has units of SEIMENS
8. A CC Amplifier has highest current
gain but lowest power gain
9. The current gain of single stage CE amplifier is
nearly equal to Beta
10. The input impedance Ri of a CE amplifier in
terms of hie,
hoe,
hre and
load resistance. ___________________.
11. The phase difference between output and input
voltages of a CB amplifier is 0
12. According to Miller’s theorem, the feedback
capacitance when referred to input side with gain A is _Cin = C(1-A)
13. Trans conductance gm in hybrid - π model is
defined as gm = ΔIc / ΔVBE when VCE=Constant
UNIT-2: (Multi stage amplifiers)
1. The most desirable feature of transformer
coupling is its [c]
A. Higher voltage gain B. wide frequency range C.ability to
provide impedance matching D. ability to eliminate hum from the output
2. For matching a circuit of output impedance 200Ω
with a load of 8 Ω the turn ratio of the two winding transformer should be [d ]
A. 25 B.1/25 C.1/5 D.5
3. In the initial stages of a multi stage
amplifier, we use [a ]
(a) RC coupling (b) transformer coupling (c) direct coupling (d)
None
4. The bandwidth of a single stage amplifier is
___ that of a multi stage amplifier. [ a ]
(a) more than
(b) less than (c) same as (d) none
5. The Darlington pair consists of the following
two stages [ d ]
(a) CE,CC (b)CE,CB (c)both CE (d) both CC
6. Transformer
coupling is generally used when RL is Small
7. In a two stage cascaded amplifier, each
of two cascaded stages has a voltage gain of 30 then the overall gain is _900
8. Why do we go
for multi stage amplifiers? for high gain
9. Direct coupled amplifiers are especially suited for amplifying extremely LOW frequency signals.
10. The DC
resistance of transformer coupling is
Low so it is more efficient
UNIT-3 (BJT
amplifiers-frequency response)
1. The gain bandwidth product of a two stage
amplifier is [ c ]
(a) same as that of single stage (b)
greater than that of single stage
(c) less than that of single stage (d) product of two gain bandwidth
products of each stage
2. How does the amplifier
behave for high frequencies? [ b ]
(a) high pass filter (b) low pass filter (c) band pass filter (d) None
3. The bandwidth of an
amplifier can be increased by [b ]
A. decreasing the capacitance of its
bypass capacitors B.minimizing the stray capacitance
C.increasing the input signal frequency D. cascading it
4. Lower cutoff frequency of an
amplifier is primarily determined by the [D ]
A.Internal
capacitance of the active device
B.Stray
capacitance between its wiring and ground
C.ac beta(β)
value of its active devices
D.Capacitances
of coupling and bypass capacitor
5. The main reason for the
variation of amplifier gain with frequency is [A ]
A. the presence of capacitance internal
and external B. due to interstage transformation
C. the
logarithmic increase in its output power D. miller effect
6. The alpha (α)
cut off frequency of a transistor is higher
than is beta (β) cut-off frequency
7. The alpha (α) of the transistor Decreases with the
increase in frequency
UNIT-IV (MOS
amplifiers)
1. A source
follower using FET usually has a voltage gain of _____. [b ]
(a) -1 (b) >100 (c) about -10 (d) less than 1 but
positive
2. For the
operation of enhancement only N- Channel MOSFET , value of gate voltage has to
be [ a]
A. High positive B. high negative C. low positive D.
zero
3. In depletion mode and N- Channel DE MOSFET conducts
with Vgs is
ZERO
4. A MOSFET can be easily destroyed by any Stray voltage on
its gate.
5. The positive gate operation of a N- Channel Depletion
MOSFET is known as Enhancement mode.
6. Cascade amplifier is combination of CB-CE
7. CD
amplifieris
called as source follower
8. CS amplifier produces a phase shift of 180˚
Prepared by
Dhanalakshmi and Neelima
Prepared by
Dhanalakshmi and Neelima