1.What is
amplifier?
Amplifier
is a device which is used to amplification purpose.
2.What is
amplification?
A low
strength signal is converted into strengthen signal ie) boost up process
3. List
the disadvantages of Rc phase shift Oscillator. (or)
What are
the merits of Rc phase shift Oscillator.
i. It is
ideal for frequency adjustment over a wide range.
ii. It
requires a high β transistor to overcome losses in the network.
4.What is
the difference between amplifier and oscillator/
Amplifier
is working in the negative feedback while oscillator working in the positive
feedback.
5.What is
an Oscillator?
An
Oscillator is a Circuit, which generates an alternating voltage of any desired
frequency.
It can generate an a.c output signal without requiring any externally
applied
input signal.
6.What is
a beat frequency oscillator?
Beat
frequency Oscillator (BFO) is an Oscillator in which a deserved signal
frequency such as the beat frequency produced by combining the different signal
frequencies such as on different radio frequencies.
7.What is
sustained Oscillation?
The
electrical oscillations in which amplitude does not change with time are called
as sustained oscillations.It is also called as Undamped Oscillation.
8.What is
meant by resonant Circuit Oscillators?
LC
Oscillators are known as resonant circuit oscillator because the frequency of
operation of LC Oscillator is nothing but a resonant frequency of tank circuit
or LC tank circuit produces sustained Oscillation at the resonant circuit
oscillator
9.What is
piezo electric effect?
The piezo
electric Crystals exhibit a property that if a mechanical stress is applied across
one face the electric potential is developed across opposite face.The inverse
is also live. This phenomenon is called piezo electric effect.
10.List
the disadvantages of crystal Oscillator.
It is
suitable for only low power circuits Large
amplitude of vibrations may crack the crystal.It large in frequency is only
possible replacing the crystal with another one by different frequency.
11. What
are parasitic Oscillators?
In a
practical amplifier circuit due to stray capacitances and lead inductances,
oscillations result, since the circuit conditions satisfy the Barkhavsen’s
criterion.These Oscillators are called as unwanted or parasitic Oscillations
12.What
is damped Oscillation?
The
electrical Oscillations in which the amplitude decreases with time are called
as damped Oscillation.
13.What
are the types of sinusoidal oscillator?
Mention
the different types of sinusoidal oscillator?
RC phase
shift Oscillator.
Wein
bridge Oscillator.
Hartley
Oscillator
Colpitts
Oscillator
Crystal
Oscillator
14.What
is Barkhausan criterion?
The
conditions for oscillator to produce oscillation is given by Barkhausan criterion.
They are
:
(i). The
total phase shift produced by the circuit should be 360oor 0o
(ii).The
Magnitude of loop gain must be greater than or equal to 1
i.e..A׀β׀≥1
14.Name
two high frequency Oscillators.
i.Hartley
Oscillator
ii.
Colpitts Oscillator
iii.Crystal
Oscillator
15.What
are the essential parts of an Oscillator?
i. Tank
circuit(or) Oscillatory circuit.
ii.Amplifier
(Transistor amplifier)
iiiFeedback
Circuit
16.What
is a linear waveform-shaping circuit?
The
process by which the shape of a nonsinusoidal signal is changed by passingthe
signal through the network consisting of linear elements is called Linear
WaveShaping.
17.What
is meant by multivibrator?
Multivibrators
are two stage switching circuits in which the output of the first stage is fed
to the input of the second state and vice-versa. The outputs of two stages are complementary.
18.Define
Astable multivibrator.
Astable
multivibrator is a multivibrator in which neither state is stable. There areTwo
temporary states. The circuit changes state continuously from one quasi stables
state to another at regular intervals without any triggering. This generates
continuous square waveform without any external signal.
19.Define
monostable multivibrator.
When a
trigger pulse is applied to the input circuit, the circuit state is changed abruptly
to unstable state for a predetermined time after which the circuit returned to its
original stable state automatically.
20.Define
integrator.
Integrator
is a circuit that passes low frequencies of the input and attenuates
highfrequencies. Integrator implies that the output voltage is an integral of
the input voltage.
21.What
is the use of commutating capacitors?
The
Commutating capacitors can be used to reduce the transition time in a low to high
level and vice versa
22.Define
transition time.
The time
interval during which the conduction transfer from one transistor to another
transistor is defined as transition time.
23.Define
the Bistable multivibrator.
Bistable
multivibrator signifies a circuit which can exist indefinitely in either of two
stable states and which can be induced
to make an abrupt transition from one state to other by applying an external triggering signal.
24.Define
resolving time.
It is the
minimum time interval between two consecutive trigger pulses and equals to
transition time plus the settling time.
25.What
is meant by linear wave shaping circuit?
The
action of a linear network in producing a waveform at its outputs different from
its output is known as linear wave
shaping circuit.
26.What are
different types of triggering of bistable multivibrator?
Asymmetrical
triggering.
Symmetrical
triggering
27.What
is meant by tuned amplifiers?
Tuned amplifiers
are amplifiers that are designed to reject a certain range of frequencies below
a lower cut off frequency ωL and above a upper cut off frequency ωH and allows only a narrow band of frequencies.
28.Classify
tuned amplifiers.
1.Single
tuned amplifier.
2.Double
tuned amplifier.
3.Synchronously
tuned amplifier.
4.Stagger
tuned amplifier.
29.What
are the advantages of double tuned amplifier?
In double
tuned amplifiers, the tuning is done both at the primary and secondary.The
double tuned amplifiers provide a wider bandwidth, flatter pass band and a
greater selectivity.
30.What is
the other name for tuned amplifier?
Tuned
amplifiers used for amplifying narrow band of frequencies hence it is also
known as “ narrow band amplifier” or “Band pass amplifier”.
31.What
is feedback amplifier?
The part
of the output is given to the input of the circuit called as feedback
amplifier.
32.Classify
the feedback amplifiers.
1)
Voltage series feedback amplifier
2)Current
series feedback amplifier
3)Voltage
shunt feedback amplifier
4)Current
shunt feedback amplifier
33.What
is meant by neutralization?
It is the
process by which feedback can be cancelled by introducing a current that is
equal in magnitude but 180o out of phase with the feedback signal at the input
ofthe active device. The two signals will cancel and the effect of feedback
will be eliminated. This technique is termed as neutralization.
34.What
is the application of tuned amplifiers?
The
application of tuned amplifiers to obtain a desired frequency and rejecting all
other frequency in
(i).
Radio and T .V broadcasting as tunning circuit.
(ii).
Wireless communication system.
35.List
out the types of feedback circuits.
Positive
feedback
Negative
feedback
36. Write
the advantages of negative feedback.
Higher
input and lower output impedance.
Improved
higher sensitivity
Reduced
noise
Increased
bandwidth
Reduced
distortion
37.Write
the disadvantages of negative feedback?
reduced overall circuit gain
reduced
distortion
38.Write
the equation for finding the bandwidth.
Bandwidth=
f2-f1
Where f1=
lower cut off frequency and f2= higher cut off frequency
39.What
is blocking oscillator?
The
circuit which uses a regenerative feedback, producing a single pulse or pulse
train is called a blocking oscillator.
40.Which
are the two important elements of a blocking oscillator?
1. Active
element like transistor.
2. A
pulse transformer.
41.What
is pulse transformer?
A pulse
transformer is basically a transformer which couples a source of pulses of electrical
energy to the load, keeping the shape and other properties of pulses unchanged.Thevoltage
level of the pulse can be raised or
lowered by designing the proper turnsratio for the pulse transformer.
42.Define
differentiator.
Differentiator
is a circuit that passes high frequencies of the input and attenuates low
frequencies. It implies that the output voltage is the differential of the
input.
43.What
is meant by clippers?
The
circuit with which the waveform is shaped by removing a portion of the input
signal without distorting the removing part of the alternating waveform is
called a clipper.
44.What
is meant by clampers?
Clamping
network shifts (clamp) a signal to a different d.c level, i.e., it introduces a
d.c level to an a.c signal.Hence,the clamping network is known as d.c restorer.
45.What
is delay time?
The time
required for the current to rise to 10% of its maximum (saturation) value Ics is called the delay time td.
46.What
is the total turn on time?
The total
turn on time is ton is the sum of the delay time and rise time,ton= td+ tr Where,td=
Delay time.
tr =Rise
time.
47.What
is storage time?
The
interval that elapses between the transition of the input waveform and the
time when
the collector current has dropped to 90 % of total output is called the storage
time ts.
48.Define
transition time.
The time
interval during which the conduction transfer from one transistor to another
transistor is defined as transition time.
49.What
is Leading edge response?
At start
there is an overshoot and then the pulse settles down. The response till it settles
down after the overshoot is called leading edge response.
50.What
is trailing edge response?
The
response generally extends below the zero amplitude after the end of pulse width
is called back swing. The portion of response from backswing till it settes
down is trailing edge response.
51.What
is flat top response?
The
portion of the response between the trailing edge and the leading edge is
called flat top response.
52.Define
rise time of a pulse.
The rise
time is an important parameter related to this part of the response.It is
defined
by the time required by the pulse to
rise from 10 % of its amplitude to 90 % of its amplitude.
53.What
is current time base generator?
The
circuit which produces current which linearly increases with time is called
current time base generator.
54.What
are the application of the blocking oscillator?
The
blocking oscillator can be used as low
impedance switch used to discharge a capacitor very quickly. To produce large
peak power pulses, both the types of oscillators cab be used.The output of the blocking
oscillator can be used to produce gating waveform with very lowmark space ratio.It may
be used as frequency divider or counter in digital circuits.
55.List
varies sweep circuits
Exponential
charging circuit
Constant-current
charging circuit.
Miller
circuit
poot
strap circuit
Inductor
circuit.
56.What
do you mean by voltage time base generators?
Circuits
used to generate a linear variation of voltage with time are called voltage
time base generators.
57.Define
resonance.
The
reactance of the capacitor equals that of the inductor reactance.
i.e ωC. =
1 / ωL.
58.What
is Quality factor?
The ratio
of inductive reactance of the coil at resonance to its resistance is known as
quality factor.Q = XL/ R
59.Define
gain bandwidth product of a tuned amplifier.
The gain
bandwidth(GBW) product is a figure of merit defined in terms of mid band gain
and upper 3-db frequency fh as GBW = | Aimfh| = gm/ 2πc
60.What
is the other name for tuned amplifier?
Tuned
amplifiers used for amplifying narrow band of frequencies hence it is also
known as “ narrow band amplifier” or “Band pass amplifier”.
61.What
is unilateralisation?
It is the
phenomenon by which a signal can be transmitted from the input to the output alone and not viceversa. In an unilateralised
amplifier both resistive and reactive effects are cancelled.
62.What
is stagger tuned amplifier?
In this
configuration one or more tuned amplifiers are cascaded each amplifier stage is
tuned to different frequencies. This results in decreased gain and increased bandwidth.
63.What
is the effect of ‘Q’ on stability?
Higher
the value of Q,provides better selectivity, but smaller bandwidth and larger gain. Hence it provides less stability.
64.What
is meant by unloaded and loaded Q of tank circuit.[ APR –2003 ]
Unloaded
Q is the ratio of stored energy to dissipated energy in a reactor or resonator.
The loaded Q (or) QL of a resonator is determined by how tightly the resonator
is coupled to its terminations.
65.Mention
the applications of class ‘c’ tuned amplifier.
One of
the most common applications for mixer is in radio receivers. The mixer is used to convert incoming signal to a lower
frequency where it is easier to obtain the high gain and selectivity required. Mixer
circuits are used to translate signal frequency to some lower frequency or to
some higher frequency. When it is used to
translate signal to lower frequency it is called down converter. When it is
used to translate signal to higher frequency, it is called up converter.
66.Mention
the need for stagger-tuned amplifier.
The
double tuned amplifier gives greater 3 db bandwidth having steeper sides
andflat top. But alignment of double tuned amplifier is difficult. To overcome
this problem two single tuned amplifiers are cascaded.
67.What
is principle of Hazel tine neutralization?
Hazel
tine introduced a circuit in which the troublesome effect of the collector to
base capacitance of the transistor was neutralized by introducing a signal
which cancels the signal coupled through the collector to base capacitance.
68.List
the performance measure of a tuned amplifier.
Selection
of a desired radio frequency signal.
Effective
quality factor.
Gain
Bandwidth.
69.What
are the characteristics of an ideal tuned amplifier?
Selects a
single radio frequency and amplifiers the same by rejecting all other
frequencies.
Bandwidth
is zero.
Harmonic
distortion is zero.
70.Write
down the relationship between bandwidth and effective Q of a tuned amplifier?
Bandwidth
= ωo/ Q effective.
71.What
are the different methods of coupling? (or) Point out different methods of
coupling the load to a tuned amplifier.
The
different methods of coupling the load to a tuned amplifier are:
Capacitive
coupling.
Inductive
coupling.
72.Why
tuned amplifier cannot be used at low frequency?
For low
frequencies the size L and C are large. So the circuit will be bulky and
expensive,
hence the tuned amplifiers cannot be used at low frequency.
73.What
is the need for differential amplifiers?
Differential
amplidiers are small signal direct coupled amplifiers used to amplify the
difference between two signals. The need for differential amplifier arises in
physical measurements, instrumentation amplifiers and medical instrumentation.
74.What
are the advantages of Differential Amplifiers?
* High voltage
gain.
* High
input impedence
* High
Bandwidth
* Good
bias stability.
75.Define
CMRR.
Common
Mode Rejection Ratio(CMRR) is the ability of the differential amplifiers to
reject the common mode signals. It is defined as the ratio of difference mode gain
Ad to common mode gain Ac.
76.Why
Differential amplifiers are widely used in Integrated Circuits?
It has
good bias stability and good voltage gain without the use of large bypass capacitors.
Hence it is used in ICs.
77.What
are the basic elements of power supply ?
(i)
Transformer
(ii)
Rectifier.
(iii)
Filter.
78.What
is ripple factor(Υ)?
Ripple
factor (γ) may be defined as the ratio of the root mean square(rms) value of
the ripple voltageto the absolute valueof the dc component of the output
voltage, usually expressed as a percentage. However, ripple voltage is also
commonly expressed as the peak to peak value. This is largely because
peak-to-peak is both easier to measure on an oscilloscope and is simpler to calculate theoretically. Filter
circuits intended for the reduction of ripple are usually called smoothing circuits.
79.What
is a rectifier?
A
rectifier is an electrical device that converts alternating current (AC), which
periodically reverses direction, to direct current(DC), which flows in only one
direction. The process is known as rectification.
80.Define
SMPS .
A
switched-mode power supply(switching-mode power supply, SMPS, or simply
switcher) is an electronic power supply that incorporates a switching regulator
in order to be highly efficient in the conversion of electrical power.An SMPS
is usually employed to efficiently provide a regulated output voltage,
typically at a level different from the input voltage
81.
Define an operational amplifier.
An
operational amplifier is a direct-coupled, high gain amplifier consisting of
one or more differential amplifier. By properly selecting the external
components, it can be used to perform a variety of mathematical operations.
82.Mention
the characteristics of an ideal op-amp.
*
Openloop voltage gain is infinity.
*Input impedance is infinity.
*Output impedance is zero.
*Bandwidth is infinity. *Zero offset.
83.Define
input offset voltage.
A small
voltage applied to the input terminals to make the output voltage as zero when
the two input terminals are grounded is called input offset voltage.
84.Define
input offset current.
The
difference between the bias currents at the input terminals of the op-amp is
called as input offset current.
85.What
is an amplifier?
An
amplifier is a device which produces a large electrical output of
similarcharacteristics to that of the input parameters.
86. How
are amplifiers classified according to the input?
1. Small
– signal amplifier
2. Large
–signal amplifier
87.How
are amplifiers classified according to the transistor configuration?
Common
emitter amplifier 2. Common base amplifier 3. Common collector
Amplifier
88. What
is the different analysis available to analyze a transistor?
1. AC
analysis 2. DC analysis
89.What
is feed back?
It is the
process of injecting some energy from the output and then returns it back tothe
input.
90.What
is the disadvantage of negative feed back?
Reduces
amplifier gain.
91.Define
sensitivity.
It is the
ratio of percentage change in voltage gain with feedback to the percentage change
in voltage gain without feed back.
92.Define
Desensitivity.
It is the
ratio of percentage change in voltage gain without feedback to thepercentage change
in voltage
93.What
is biasing?
To use
the transistor in any application it is necessary to provide sufficient voltage
and current to operate the transistor. This is called biasing.
94. What
is the necessary of the coupling capacitor?
It is
used to block the c signal to the transistor amplifier. It allows a c
&blocks the d c.
95.Whatis
reverse saturation current?
The
current due to the minority carriers is called the reverse saturation current
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