ELECTRONIC CIRCUITS (1)
Crossover Network
A pair of filter common on high fidelity system which separate audio frequency band signals into two separate groups, where on is fed to tweeter and other to woofer is called
Hum in the circuit
A pulsating dc applied to power amplifiers causes
Collector has reverse bias
A transistor amplifier has high output impedance because
DC power into AC Power
A transistor converts
Radio Frequency
A tuned amplifier is used in what application
LC Tank
A tuned amplifier uses what load
Push-pull amplifier
A two-transitor class B power amplifier is commonly called
Band pass filter
A type of filter which is having a single continuous transmission band with neither the upper nor the lower cut-off frequencies being zero or infinite is called
Relaxation oscillator
A type of oscillator wherein the frequency is determined by the charge and discharge of resistor-capacitor networks used in conjunction with amplifiers or similar devices
bigger
AC load line has ____ slope compared ot dc load line
Harmonic
Amplitude distortion is otherwise known as ____ distortion
Prevent induction due to stray magnetic fields
An AF transformer is shielded to
Zero
An ammeter's ideal resistance should be
Coupling
An electronic transfer from one stage to the next is termed as _____
Positive feedback
An oscillator oscillates due to
Undamped
An oscillator produces _____ oscillations
to reduce distortion
Basic purpose of applying negative feedback to an amplifier
Electrolytic
Capacitors are used in transistor amplifiers
Less than one-half the entire input cycle
Class C in an amplifier whose output current flows or
100%
Class C operation can have ___ percent efficiency
Transformer
Coupling that provides maximum voltage gain
It gives distorted output
Disadvantage of impedance matching
Crystal Circuit
For a constant output frequency, the simplest sinusoidal oscillator circuit to construct is the
1/(4πsqrt(LC))
For constant-k high-pass filter, cut-off frequency is given by
Class C
Generally, tuned amplifiers are operated in
Radio Receivers
Hartley Oscillator is commonly used in
Class C
If a transistor is operated in such a way that output current flows for 160deg of the input signal, then it is
A/(1 + Aβ)
If gain without feedback and feedback factor are A and β respectively, then gain with negative feedback is given by
0
If the noise factor of an ideal amplifier expressed in dB, then it is
Low output
Important limitation of crystal oscillator
the same as the input
In class A amplifier, the output signal is
Class A
In multistage amplifier, if the stages have R and C component only, ____ operation is apparent
thin base
In order to have more voltage gain from a transistor amplifier the transitor used should have
R and C
In phase shift oscillator, what are the frequency determining elements
Capacitance
In practice, what is normally varied in order to change the frequency of oscillation
RC
In the initial stages of a multistage amplifierm ___ coupling is used
step down
In transistor amplifiers, what transfoerm is used t for impedance matching
Darlington pair
Increasing the overall Beta is an advantage of
Two
Multistage amplifier uses at least how many transistors
Amplifiers
Negative feedback is employed in
Class C
Non-linear type of amplifier
the middle
Operating point is generally located at ____ of dc load line in Class A
Positive
Oscillator employs ____ feedback
Klystron
Oscillator is used in order to produce frequencies in the microwave region
Positive feedback
Oscillators operate on the principle of
Class AB
Portion of signal is only required, such as the synchronizing pulse separator of a television receiver
voltage
RC coupling is used for ____ amplification
Electrical size of coupling capacitor becomes very large
Reason why RC coupling is not used to amplify extremely low frequencies
hie
Represent common-emitter small signal input resistance
smaller
The ____ the voltage regulation, the better the operation of voltage supply circuit
more than
The bandwidth of a single stage amplifier is ____ that of multistage amplifier
Campbell and Wagner
The basic concept of electric wave filter orginated by
open
The capacitors are considered ____ in the dc equivalent circuit of a transistor amplifier
Alpha times Emitter current plus Leakage current
The collector current in a common base configuration is equal to
prevent attenuation of low frequency
The coupling capacitor Cc must be large enough to ____ in an RC coupling scheme
two signals 180° out of phase to transistors of push-pull circuit
The driver transformer has center-tapped secondary to provide
Frequency
The ear is not sensitive to _____ distortion
50 to 78.5%
The efficiency of class AB operation has maximum of b/w ____ percent
independent of
The feedback circuit is _____ frequency
transformer
The final stage of an amplifier uses ____ coupling
poor
The frequency response of transfoer coupling is
Wien bridge
The frequency stability of the oscillator output is maximum in ___ oscillator
Reduces
The gain of an amplifier ____ when negative feedback is added
Closed loop
The gain of an amplifier with feedback is known as ____ gain
coupling
The input capacitor in an amplifier is called ____ capacitor
decreases
The input impedance of an amplifier ____ when negative current feedback is applied
increases
The input impedance of an amplifier ____ when negative voltage feedback is applied
CC
The input impedance of which amplifier depends strongly on load resistance
Re, re and β
The input resistance of a common emitter amplifier is affected by
Unity
The largest theoretical voltage gain obtained with common collector amplifier
Change in temperature can cause thermal instability
The number of stages that can be directly couples is limited because
Armstrong circuit
The simplest variable-frequency sinusiodal oscillator is the
Less than
The value of collector load resistance in a transistor amplifier is ____ the output impedance of the transistor
Unity
The voltage gain of common collector config
Is constant
The voltage gain over mid-frequency range in an RC coupled amplifier ____
Direct
To amplify dc signals, multistage amplifier uses what coupling
very much greater than 1
To obtain good gain stability in a negative feedback amplifier, Aβ is
generator output level
To obtain the frequency response curve of an amplifier ____ is kept constant
Frequency
Transformer coupling introduces what type of distortion
small
Transformer coupling is generally employed when load resistance is
Power
Transformer coupling is used for ____ amplification
Impedance matching can be achieved
Transformer coupling provides high gain because
Common Base and Common-collector
Transistor configuration that offers no phase reversal at the output
Both positive and negative
Type of feedback used in Wien bridge oscillator
more than 10,000
Typical Q of crystal
about 10μF
Typical value of coupling capacitor Cc in RC Coupling
Push-pull amplifier
Usually employed at the output stage of an amplifier
Amplifier
What circuit increases the peak to peak voltage, current or power of a signal
Biasing conditions will change
What happens if the input capacitor of transistor amplifier is short circuited
Voltage is developed due to mechanical stress
What is piezoelectric effect in crystal
X
What is the axis that connects the corners of a crystal
Power gain
What is the main consideration in the output stage of an amplifier
Quiescent point
What is the operating point in the characteristic curve
Operating point
What is the point of intersection of dc and ac load lines called
To separate bias of one stage from another
What is the purpose of RC or transformer coupling
Moderate
What is the ratio of output to input impedance of CE amplifier
Transit time
What is the time taken by the electrons or holes to pass from emitter to collector
Comparator
What linear circuit compares two signal and provides a digital level output depending on the relationship of the input signals
Logic Probe
What piece of equipment in an oscilloscope is used to indicate pulse condition in a digital logic circuit
Transformer
What type of coupling is generally used in power amplifiers
Decreases
When negative voltage feedback is applied to an amplifier its output impedance
D/(1 + Aβ)
When non-linear distortion in an amplfiier is D without feedback, with negative voltage feedback it will be
Either Class A or B
Which amplifier is considered linear?
Class A
Which amplifier whose output current flows for the entire cycle
Direct
Which coupling has the best frequency response
Low voltage gain
Which describe common collector amplifier
Biasing
Which is used to establish a fixed level of current or voltage in a transistor
Gain-bandwidth product
Which of the following is considered an amplifier figure of merit
Current gain
Which of the following is provided by a CB transistor amplifier
Class C
Which power amplifier has the highest collector efficiency
DC resistance is low
Why transformer coupling provides high frequency
Common-base
configuration with lowest current gain
Class C
little use in general purpose amplifiers, but used in high frequency oscillators
Class B
used either where the signal needs to be cut in half, such as in pulse detector or noise detectors or where push-pull operation of two stges is required
Class A
used for general amplification where no distortion can be tolerated
