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AB-19
CASCODE AMPLIFIER
ANALOG LAB
EXPERIMENT BOARD
Ver. 1.0
An ISO 9001: 2000 company
94-101, Electronic Complex, Pardesipura INDORE-452010, India.
AB-19
Tel.: 91-731-2570301 Fax: 91-731-2555643
Email: [email protected] Web: www.scientech.bz
Scientech Technologies Pvt. Ltd.
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AB-19
CASCODE AMPLIFIER
AB-19
TABLE OF CONTENTS
1.
Introduction
3
2.
Theory
5
3.
Experiment 1
To study the operation of Cascode Amplifier
8
4.
Experiment 2
To study the frequency response of
Cascode Amplifier
10
Datasheet
12
5.
Warranty
14
6.
List of service Centers
15
7.
List of Accessories with AB-19
16
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AB-19
INTRODUCTION
AB-19 is a compact, ready to use CASCODE AMPLIFIER experiment
board. This board is useful for students to understand the working and
operation of various cascade amplifier stages. It can be used as stand alone
unit with external DC power supply or can be used with SCIENTECH
ANALOG LAB ST-2612 which has built in DC power supply, AC power
supply, function generator, modulation generator, continuity tester, toggle
switches, and potentiometer.
List of Boards :
Model
AB-01
AB-02
AB-03
AB-04
AB-05
AB-06
AB-07
AB-08
AB-09
AB-15
AB-16
AB-17
AB-18
AB-21
AB-22
AB-23
AB-26
AB-28
AB-29
AB-30
AB-31
AB-32
AB-33
AB-41
AB-42
AB-43
Name
Diode characteristics (Si, Zener, LED)
Transistor characteristics (CB NPN)
Transistor characteristics (CB PNP)
Transistor characteristics (CE NPN)
Transistor characteristics (CE PNP)
Transistor characteristics (CC NPN)
Transistor characteristics (CC PNP)
FET characteristics
Rectifier Circuits
Common Emitter Amplifier
Common Collector Amplifier
Common Base Amplifier
RC-Coupled Amplifier
Class A Amplifier
Class B Amplifier (push pull emitter follower)
Class C Tuned Amplifier
Phase Locked Loop (FM Demodulator &
Frequency Divider/Multiplier)
Multivibrators (Astable / Monostable)
F-V and V-F Converter
V-I and I-V Converter
Zener Voltage Regulator
Transistor Series Voltage Regulator
Transistor Shunt Voltage Regulator
Differential Amplifier (Transistorized)
Operational Amplifier (Inverting / Noninverting / Differentiator)
Operational Amplifier (Adder/Scalar)
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AB-19
AB-44
AB-45
AB-51
AB-52
AB-53
AB-56
AB-65
AB-66
AB-67
AB-81
AB-82
AB-83
AB-84
AB-90
AB-91
AB-92
AB-93
Operational Amplifier (Integrator/
Differentiator)
Schmitt Trigger and Comparator
Active filters (Low Pass and High Pass)
Active Band Pass Filter
Notch Filter
Fiber Optic Analog Link
Phase Shift Oscillator
Wien Bridge Oscillators
Colpitt Oscillator
Kirchoff’s Laws (Kirchoff’s Current Law &
Kirchoff’s Voltage Law)
Thevenin’s and Maximum power Transfer
Theorem
Reciprocity and Superposition Theorem
Tellegen’s Theorem
Two port network parameter
Optical Transducer (Photovoltaic cell)
Optical Transducer (Photoconductive cell/LDR)
Optical Transducer (PhotoTransistor)
…. and many more
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AB-19
THEORY
Single amplifier circuits, such as a common emitter, common base and
common collector amplifiers are seldom found alone, as a single stage
amplifier, in any system. Generally, at least two or more than two stages
are connected in cascade combination. If the output of one amplifier is
connected (coupled) to the input of another amplifier the stages are said to
be connected in "cascade". The benefit of cascaded amplifiers is to develop
an output voltage larger than either stage alone can develop.
The gain of a single stage is not as important as the system gain. Designers
usually set individual stage gains relatively low to reduce signal distortion.
One of the very important requirements of cascade is first stage output
impedance of amplifier matches to input impedance of second stage which
is known as impedance matching. When the output impedance of previous
stage matches with the input impedance of its next stage, maximum power
is transferred.
Cascode Amplifier :
Cascode amplifier is a special case of cascade amplifier. Cascode amplifier
is a two stage amplifier, which comprises a CE amplifier driving a CB
amplifier. The CE amplifier has with significant current and voltage gain
moderate input and output impedance. The high input impedance is
desirable while the high output impedance possess some problems. The
higher the output impedance the less current can be drawn from an
amplifier without a significant drop in output voltage .The CE is used most
often for voltage amplification .It can provide a large output voltage swing.
In multistage system this output becomes the input of the next stage of the
system .The emitter resistor amplifier is similar to the CE amplifier but has
lower voltage gain and higher input impedance .Because of the feedback
present in this amplifier, internal noise generated by the transistor is almost
eliminated.
The CB amplifier has low input impedance and relatively high output
impedance. These properties are less desirable for signal amplification. If
the base is bypassed to ground with a capacitor, the amplifier has high
voltage gain but the current gain is less than unity .Thus if the source
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AB-19
driving the amplifier has a low impedance, and the load is drawing little
current, the CB can be used as a voltage amplifier .If the driving source has
a higher impedance, we can offset this undesirable effect by using a CE
amplifier to drive the CB amplifier. Thus the overall input impedance is
high.
Circuit Diagram of Cascode Amplifier :
Fig.2
In Cascode Amplifier Transistor T1 forms the CE amplifier and CB
amplifier utilizes T2 .This configuration has the advantage of increased
output resistance and wider frequency response while maintaining high
voltage gain. The input resistance of the CE stage is relatively high. The
low input impedance of the CB circuit forms the load resistance for the CE
stage .The collector current of T2 is almost equal to the collector current of
T1, which in turn drives the load (RL || Rc2) in this circuit the capacitor are
considered as short circuits. The dc source, Vcc, is set to ground potential
since we are interested in the ac component of the signals since RE is
bypassed by CE.
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AB-19
Bandwidth of a Cascode Amplifier :
Bandwidth is defined as the band of frequency over which the amplifier
gain is constant.
Fig. 3
The f1 and f2 points are also known as half power points. The half power
points are the points at which the signal amplitude has dropped to .707
percent of the maximum signal amplitude. Any frequency below the f1 or
above the f2 point is not considered a usable output from the amplifier. The
bandwidth of the amplifier is the difference between the f1 and f2 points.
Bandwidth (B) = f2 – f1
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…………….(2)
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AB-19
EXPERIMENT 1
Object :
To study the operation of Cascode amplifier.
Apparatus Required :
1.
2.
Analog board AB-19.
3.
Function Generator.
4.
Oscilloscope.
5.
2mm patch chords.
DC power supply +12V from external source or ST-2612 Analog
Lab.
Circuit Diagram :
Circuit used to study the operation of Cascode amplifier is shown below :
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AB-19
Fig.4
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Procedure :
•
Connect +12V variable dc power supplies at their indicated
position from external source or ST-2612 Analog Lab.
1.
Connect 1Vp-p, 1 KHz Sine wave signal at the input (between points
Vin and gnd) of Cascode amplifier AB-19 board and observe the
same on oscilloscope CH I.
2.
Observe the output waveform between points Vout and gnd. on
oscilloscope CH II.
3.
Calculate the Voltage Gain (AV).
Result :
Voltage Gain of Cascode amplifier [AV = Vout / Vin ] = …………………..
EXPERIMENT 2
AB-19
Object :
To study the Frequency Response of Cascode amplifier.
Apparatus Required :
1.
2.
Analog board AB-19.
3.
Function Generator.
4.
Oscilloscope.
5.
2mm patch chords.
DC power supply +12V from external source or ST-2612 Analog
Lab.
Circuit Diagram :
Circuit used to study the Frequency Response of Cascode amplifier is
shown below:
Fig.5
Procedure :
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AB-19
•
Connect +12V variable dc power supplies at their indicated
position from external source or ST-2612 Analog Lab.
1.
Connect 1Vp-p, 100Hz Sine wave signal at the input (between points
Vin and gnd) of amplifier of AB-19 board and observe the same on
oscilloscope CH I.
2.
Observe the output waveform between points Vout and gnd on
oscilloscope CH II.
3.
Increase the input frequency value and observe the output waveform
amplitude on oscilloscope
4.
Measure the maximum amplitude of the output sine wave and the
frequency range for which the output wave amplitude is 3dB down
the maximum amplitude.(this will give two valves of frequency fL
and fH, the lower 3dB frequency and higher 3dB frequency
respectively) as shown in fig.5.
5.
Calculate Bandwidth of Cascode amplifier using Eq.2
Result :
f1 (lower 3dB frequency) = ………………………...
f2 (higher 3dB frequency) = ………………………..
Bandwidth (f2 – f1) = ………………………………
DATASHEET
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AB-19
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AB-19
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AB-19
WARRANTY
1) We guarantee the instrument against all manufacturing defects during
24 months from the date of sale by us or through our dealers.
2) The guarantee covers manufacturing defects in respect of indigenous
components and material limited to the warranty extended to us by the
original manufacturer, and defect will be rectified as far as lies within
our control.
3) The guarantee will become INVALID.
a) If the instrument is not operated as per instruction given in the
instruction manual.
b) If the agreed payment terms and other conditions of sale are not
followed.
c) If the customer resells the instrument to another party.
d) Provided no attempt have been made to service and modify the
instrument.
4) The non-working of the instrument is to be communicated to us
immediately giving full details of the complaints and defects noticed
specifically mentioning the type and sr. no. of the instrument, date of
purchase etc.
5) The repair work will be carried out, provided the instrument is
dispatched securely packed and insured with the railways. To and fro
charges will be to the account of the customer.
DESPATCH PROCEDURE FOR SERVICE
Should it become necessary to send back the instrument to factory please
observe the following procedure:
1) Before dispatching the instrument please write to us giving full details
of the fault noticed.
2) After receipt of your letter our repairs dept. will advise you whether it
is necessary to send the instrument back to us for repairs or the
adjustment is possible in your premises.
Dispatch the instrument (only on the receipt of our advice) securely packed
in original packing duly insured and freight paid along with accessories and
a copy of the details noticed to us at our factory address.
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AB-19
LIST OF SERVICE CENTERS
1. Scientech Technologies P. Ltd.
90, Electronic Complex
Ph: (0731) 5202959
Pardesipura,
Email: [email protected]
INDORE – 452010
2. Scientech Technologies P. Ltd.
First Floor,
Ph.: (011) 26513912, 26864943
14, Uday Park,
Fax: (011) 26864943.
NEW DELHI – 110049
Email: [email protected]
3. Scientech Technologies P. Ltd.
New no.2, Old no.10, 4th street Ph.: (044) 52187548, 52187549
Venkateswara nagar, Adyar
Fax: (044) 52187549
CHENNAI – 600025
Email: [email protected]
4. Scientech Technologies P. Ltd.
202/19, 4th main street
Ph.: (080) 51285011
Ganganagar,
Fax: (080) 51285022
BANGALORE- 560032
Email: [email protected]
5. Scientech Technologies P. Ltd.
First floor, L block
Ph.: (022) 56299547
Ranjit studio compound,
Fax: (022) 24155984
Dada Saheb Phalke road,
Email: [email protected]
Dadar (East)
MUMBAI – 400014
6. Scientech Technologies P. Ltd.
988, Sadashiv Peth,
Ph.: (020) 24461673
Gyan Prabodhini Lane,
Fax: (020) 24482403
PUNE – 411030
Email: [email protected]
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AB-19
LIST OF ACCESSORIES
1.
2.
3.
2mm patch cord (red)………………………………………...1 Nos.
2mm patch cord (blue)………………….……………………2 Nos.
2mm patch cord (black)……………………………………...3 Nos.
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