Amplifier and Oscillator Circuit Design and Testing

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2019
Electronic
Circuits and
Devices
Electronics
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Table of Contents
Introduction................................................................................................................................5
LO1: Operational Properties of Different Amplifier Circuits....................................................6
Main Types of Operational Amplifiers-T1 (1).......................................................................6
Voltage OP-AMP...............................................................................................................6
Current Amplifiers.............................................................................................................6
Power Amplifiers...............................................................................................................6
Applications of Main Types of An Amplifier........................................................................7
Voltage Amplifier..............................................................................................................7
Current Amplifier...............................................................................................................7
Power Amplifier.................................................................................................................7
Working Principle of Main Types of An Amplifier-T1 (2)...................................................7
Voltage Amplifier..............................................................................................................7
Current Amplifier...............................................................................................................7
Power Amplifier.................................................................................................................7
Calculation of The Maximum Gain of an OP-AMP With Maximum Value Of Vs-T1 (3)...8
Given Data.........................................................................................................................8
Required Data.....................................................................................................................8
Solution..............................................................................................................................8
Class-A Op-Amp-T1 (4)........................................................................................................9
Class “A” Amplifier Design...............................................................................................9
Simulating A Class “A” OP-Amplifier............................................................................10
Results..............................................................................................................................10
Design Parameters Effect On The Performance Of Class “A” OP-Amplifier.................10
Analysis And Evaluation Of The Class “A” Amplifier.......................................................11
LO2: Feedback Types and Its Effect on An Amplifier’s Performance....................................12
Output Voltage of a Feedback Amplifier-T2 (1).................................................................12

Given DATA....................................................................................................................12
Required...........................................................................................................................12
Solution............................................................................................................................12
Output Voltage Of A Summing Amplifier-T2 (2)...............................................................12
Given................................................................................................................................12
Required...........................................................................................................................13
Solution............................................................................................................................13
Simulation Of Feedback Amplifier......................................................................................13
When Rf =2kΩ.................................................................................................................13
When Rf =5kΩ.................................................................................................................14
Effect on Gain and Performance......................................................................................14
Evaluation of The Results................................................................................................14
Limitations on The Parameters........................................................................................14
LO3: Operations and Applications of Oscillators....................................................................15
Oscillators............................................................................................................................15
Classification of Oscillators-T3 (1)......................................................................................15
Armstrong Oscillator........................................................................................................15
Uses of Armstrong Oscillator...........................................................................................15
Hartley Oscillator.............................................................................................................15
Uses of Hartley Oscillator................................................................................................16
Colpitts Oscillator............................................................................................................16
Uses of Colpitts Oscillator...............................................................................................16
Oscillating Gain and “f” of an Ideal Amplifier-T3 (2).........................................................16
Derivation of “Frequency”...............................................................................................16
Derivation of “f”...............................................................................................................17
Parameters Affecting the Execution Of An Oscillator-T3 (3).............................................17
Simulation of An Oscillator-T3 (4)......................................................................................18

Analysis of The Oscillator Circuit’s Performance...........................................................18
LO4: Processes to Testify Electrical Circuits and Its Devices.................................................19
Comparison of An IC Named LM741 With an Operational Amplifier Which Is in Ideal
Condition-T4 (1)..................................................................................................................19
Parameters of The LM741 OP-AMP-T4 (2)........................................................................19
Simulation of An LM741 OP-AMP –T4 (3)........................................................................20
Difference between the calculated and the simulated values...........................................20
Conclusion............................................................................................................................22
List of Figures
Figure 11 Hartley oscillator.....................................................................................................14
Figure 12 Colpitt oscillator......................................................................................................14
Figure 13 REULTS OF LM741...............................................................................................18
List of Tables
Table 1 Comparison between LM741 and ideal op-amp.........................................................18
Table 2 Difference table...........................................................................................................20

Introduction
Amplifiers tells us those circuits which produces and increases the amplitude of the given
input signal. Amplifiers are all not the same and they are classified with respect to their
manners of operation. There are many types of electrical circuits which are classified as
amplifiers derived from operational amplifiers and small signal amplifiers ended equal to
signal with high power amplifiers.
Figure 1 Amplifier circuit

LO1: Operational Properties of Different Amplifier Circuits
Main Types of Operational Amplifiers-T1 (1)
The main types if amplifier are as follow: -
Voltage OP-AMP
Voltage amplifier magnifies output voltage waveform as compare to input voltage, but in
such a case output current given may or may not be bigger than the input current.
Figure 2 Voltage amplifier
Current Amplifiers
Current amplifier magnifies output current waveform as compare to input current, but in such
a case the output voltage waveform given may or may not be bigger than the waveform of
input voltage.
Figure 3 Current OP-amplifiers
Power Amplifiers
Power amplifier mainly amplifies product of current and voltage at output as compare to the
product of current and voltage at input, but in such a case the current and voltage may get
increased or decreased at output. Such as A Class, B Class, AB Class, D Class are some
examples of power amplifiers.

Figure 4 Power amplifier
Applications of Main Types of An Amplifier
Voltage Amplifier
 Boosting an audio signal
 Increased voltage
 Increased power
Current Amplifier
 Better bass output
 Laser and water jet cutting machines
 Sensor systems
Power Amplifier
 RF systems
 AM, FM & TV broadcast
 Microwave radar
Working Principle of Main Types of An Amplifier-T1 (2)
Voltage Amplifier
Mainly a type of common emitter amplifiers which can be determined by the ratio of
collector junction and emitter junction ratios are said to be voltage amplifiers, such that signal
boosting before it is send to a speaker.
Current Amplifier
Current amplifier can be realized using transistors. It amplifies the current without fiddling
with the voltage levels.
Power Amplifier
The simple belief on which a power amplifier works is altering the DC power that is being
drawn from the power supply into an AC signal of voltage transported to the load. Efficiency
is higher, although efficiency rating of an ideal power op-amplifier is hundred percent
(Amos, and James, 2013).

Calculation of The Maximum Gain of an OP-AMP With Maximum Value Of Vs-
T1 (3)
Figure5 OP-AMP
Given Data
R 1+R 2=10 kΩ Vs=1 volt Io=200 mAmpereRL=50 Ω
Required Data
Gain=?
Solution
Vo=(1+( R 2
R 1 ))∗Vs¿( 200 mAmpere)∗(50 Ω)¿ 10 Volts
Gain=Vo /Vs ¿(R 1+ R 2)/R 1 AV =10

Class-A Op-Amp-T1 (4)
Class “A” Amplifier Design
Above figure is the modest form of class“A” OP-Amp circuit. Transistor which is single
ended is used for the calculation of its output which is connected with a resistive load that is
directly associated to the junction of collector (Raffo, et. al., 2010). Whenever the transistor
will be in “on” condition it will drop the output current from the junction of collector which
will result in a voltage drop on the resistance of emitter limiting the output to be capable of
giving negative in it..

Simulating A Class “A” OP-Amplifier
Figure 6 Class”A”OP- amplifier
Results
Figure 7 Results of Class A OP-amplifier
Design Parameters Effect On The Performance Of Class “A” OP-Amplifier
Transistor Choice
A “2N3904-npn” is a transistor having lesser signal but the tranistor choice deponds mainly
on the required output and load of the given transistor.By interpreting the details of a suitable
transistor we can select a desied transistor.
DC voltage dependency

Class A op-amplifiers which are normally used are of DC supplies of 6-12 volts. Transistor’s
VceoMax should be greater than the power rating written before, we can select it by reading
datasheet of the transistor.
Capacitance value of Capacitor1 and Capacitor2
Main purpose of using these capacitors are allowing the ac signals and then blocking the dc
signals at the input such that the output voltage will not disturb the biasing for the amplifiers
Capacitance value of Capacitor3
Main purpose of using capacitor3 is preventing our voltage of ac signal by presenting it on
the emitter resistor Re.It will definately lesser down the input signal and will also lesser down
the amplifier’s gain.
Output Impedence
RL is the output resistance of an amplifier, the coupling capacitors dont have an effect on the
output resistance because of its lower value.
Analysis And Evaluation Of The Class “A” Amplifier
The graph shown above is simply the simulated graph of a common emitter amplifier, the
graph shown in left section is the input signal, and the one shown on the right is the output
signal . There is a small difference in both signals because of non-linearity involved in the
signal. Instantaneous power is calculated by the sum of both dissipated supplies, average
value of voltage is about 12V.

LO2: Feedback Types and Its Effect on An Amplifier’s Performance
Output Voltage of a Feedback Amplifier-T2 (1)
Figure 8 Feedback OP-amplifier
Given DATA
Vs=2 mVOLTS RL=10 kΩ R 1=1 kΩR 2=49 kΩ
Required
V0=?
Solution
Vo=(1+ ( R 2
R 1 ))∗Vs
¿( 50∗(2))∗(10−3 )
¿ 10 V OLTS
Output Voltage Of A Summing Amplifier-T2 (2)
Given
Figure 9 Summing Amplifier
Required
Vo=?