Electronics and Communication Engineering is the Branch of Engineering. Electronics and Communication Engineering field requires an understanding of core areas including Engineering Graphics, Computer Programming,Electronics Devices and Circuits-I, Network Analysis, Signals and Systems, Communication Systems, Electromagnetics Engineering, Digital Signal Processing, Embedded Systems, Microprocessor and Computer Architecture. Ekeeda offers Online Mechanical Engineering Courses for all the Subjects as per the Syllabus. Visit : https://ekeeda.com/streamdetails/stream/Electronics-and-Communication-Engineering
Introduction
Band Pass Amplifiers
Series & Parallel Resonant Circuits & their Bandwidth
Analysis of Single Tuned Amplifiers
Analysis of Double Tuned Amplifiers
Primary & Secondary Tuned Amplifiers with BJT & FET
Merits and de-merits of Tuned Amplifiers
Tuned Amplifiers : Introduction, Q-Factor, small signal tuned amplifier, capacitance single tuned amplifier, double
tuned amplifiers, effect of cascading single tuned amplifiers on band width, effect of cascading double tuned
amplifiers on band width, staggered tuned amplifiers, stability of tuned amplifiers, wideband amplifiers
Introduction
Band Pass Amplifiers
Series & Parallel Resonant Circuits & their Bandwidth
Analysis of Single Tuned Amplifiers
Analysis of Double Tuned Amplifiers
Primary & Secondary Tuned Amplifiers with BJT & FET
Merits and de-merits of Tuned Amplifiers
Tuned Amplifiers : Introduction, Q-Factor, small signal tuned amplifier, capacitance single tuned amplifier, double
tuned amplifiers, effect of cascading single tuned amplifiers on band width, effect of cascading double tuned
amplifiers on band width, staggered tuned amplifiers, stability of tuned amplifiers, wideband amplifiers
Negative amplifiers and its types Positive feedback and Negative feedbackimtiazalijoono
Negative amplifiers
What is Feedback?
Positive feedback
Negative feedback
Feedback Circuit
Principles of Negative Voltage Feedback In Amplifiers
Gain of Negative Voltage Feedback Amplifier
Advantages of Negative Voltage Feedback
Principles of Negative Current Feedback
Current Gain with Negative Current Feedback
Infomatica, as it stands today, is a manifestation of our values, toil, and dedication towards imparting knowledge to the pupils of the society. Visit us: http://www.infomaticaacademy.com/
Electrical Engineering is the Branch of Engineering. Electrical Engineering field requires an understanding of core areas including Thermal and Hydraulics Prime Movers, Analog Electronic Circuits, Network Analysis and Synthesis, DC Machines and Transformers, Digital Electronic Circuits, Fundamentals of Power Electronics, Control System Engineering, Engineering Electromagnetics, Microprocessor and Microcontroller. Ekeeda offers Online Mechanical Engineering Courses for all the Subjects as per the Syllabus Visit : https://ekeeda.com/streamdetails/stream/Electrical-Engineering
Electrical Engineering is the Branch of Engineering. Electrical Engineering field requires an understanding of core areas including Thermal and Hydraulics Prime Movers, Analog Electronic Circuits, Network Analysis and Synthesis, DC Machines and Transformers, Digital Electronic Circuits, Fundamentals of Power Electronics, Control System Engineering, Engineering Electromagnetics, Microprocessor and Microcontroller. Ekeeda offers Online Mechanical Engineering Courses for all the Subjects as per the Syllabus. Visit : https://ekeeda.com/streamdetails/stream/Electrical-and-Electronics-Engineering
Electrical current, voltage, resistance, capacitance, and inductance are a few of the basic elements of electronics and radio. Apart from current, voltage, resistance, capacitance, and inductance, there are many other interesting elements to electronic technology. ... Use Electronics Notes to learn electronics online.
Negative amplifiers and its types Positive feedback and Negative feedbackimtiazalijoono
Negative amplifiers
What is Feedback?
Positive feedback
Negative feedback
Feedback Circuit
Principles of Negative Voltage Feedback In Amplifiers
Gain of Negative Voltage Feedback Amplifier
Advantages of Negative Voltage Feedback
Principles of Negative Current Feedback
Current Gain with Negative Current Feedback
Infomatica, as it stands today, is a manifestation of our values, toil, and dedication towards imparting knowledge to the pupils of the society. Visit us: http://www.infomaticaacademy.com/
Electrical Engineering is the Branch of Engineering. Electrical Engineering field requires an understanding of core areas including Thermal and Hydraulics Prime Movers, Analog Electronic Circuits, Network Analysis and Synthesis, DC Machines and Transformers, Digital Electronic Circuits, Fundamentals of Power Electronics, Control System Engineering, Engineering Electromagnetics, Microprocessor and Microcontroller. Ekeeda offers Online Mechanical Engineering Courses for all the Subjects as per the Syllabus Visit : https://ekeeda.com/streamdetails/stream/Electrical-Engineering
Electrical Engineering is the Branch of Engineering. Electrical Engineering field requires an understanding of core areas including Thermal and Hydraulics Prime Movers, Analog Electronic Circuits, Network Analysis and Synthesis, DC Machines and Transformers, Digital Electronic Circuits, Fundamentals of Power Electronics, Control System Engineering, Engineering Electromagnetics, Microprocessor and Microcontroller. Ekeeda offers Online Mechanical Engineering Courses for all the Subjects as per the Syllabus. Visit : https://ekeeda.com/streamdetails/stream/Electrical-and-Electronics-Engineering
Electrical current, voltage, resistance, capacitance, and inductance are a few of the basic elements of electronics and radio. Apart from current, voltage, resistance, capacitance, and inductance, there are many other interesting elements to electronic technology. ... Use Electronics Notes to learn electronics online.
The performance obtainable from a single-stage amplifier is often insufficient for many applications, hence several stages may be combined forming a multistage amplifier. These stages are connected in cascade, i.e. output of the first stage is connected to form input of second stage, whose output becomes input of third stage, and so on.
thank u
Hansraj MEENA
Coupling of Amplifiers- Direct coupled amplifiertanishashukla147
The topic is part of electronics and deals with the coupling of two-stage or multi-stage amplifiers without the use of any resistors, capacitors or transformers.
Design & Implementation of Zero Voltage Switching Buck ConverterIJERA Editor
Zero voltage switching (ZVS) buck converter is more preferable over hard switched buck converter for low power, high frequency DC-DC conversion applications. In Zero voltage switching converter, turn on & turn off of a switch occurs at zero voltage that results in lower switching losses. In this converter soft switching is achieved by using resonant components. The optimal values of resonant components are determined by using electric functions derived from circuit configuration. This type of soft switched resonant converter offers very low electromagnetic interference (EMI).This study presents the circuit configuration with least components to realize highly efficient zero voltage switching resonant converter. It’s feasibility is confirmed with the developed proto type model and experimental results are verified.
Soft Switched Multi-Output Flyback Converter with Voltage DoublerIJPEDS-IAES
A novel multi-output voltage doubler circuit with resonant switching
technique is proposed in this paper. The resonant topology in the primary
side of the flyback transformer switches the device either at zero voltage or
current thus optimizing the switching devices by mitigating the losses. The
voltage doubler circuit introduced in the load side increases the voltage by
twice the value thereby increasing the load power and density. The proposed
Multi-output Isolated Converter removes the need for mutiple SMPS units
for a particular application. This reduces the size and weight of the
converters considerably leading to a greater payload. This paper aims at
optimizing the proposed converter with some design changes. The results
obtained from the hardware prototype are given in a comprehensive manner
for a 3.5W converter operating at output voltages of 5V and 3.3V at 50 kHz
switching frequency. The converter output is regulated with the PI controller
designed with SG3523 IC. The effects of load and line regulation for ±20%
variations are analyzed in detail.
Hardware Analysis of Resonant Frequency Converter Using Isolated Circuits And...IJERD Editor
-LLC resonant frequency converter is basically a combo of series as well as parallel resonant ckt. For
LCC resonant converter it is associated with a disadvantage that, though it has two resonant frequencies, the
lower resonant frequency is in ZCS region[5]. For this application, we are not able to design the converter
working at this resonant frequency. LLC resonant converter existed for a very long time but because of
unknown characteristic of this converter it was used as a series resonant converter with basically a passive
(resistive) load. . Here, it was designed to operate in switching frequency higher than resonant frequency of the
series resonant tank of Lr and Cr converter acts very similar to Series Resonant Converter. The benefit of LLC
resonant converter is narrow switching frequency range with light load[6] . Basically, the control ckt plays a
very imp. role and hence 555 Timer used here provides a perfect square wave as the control ckt provides no
slew rate which makes the square wave really strong and impenetrable. The dead band circuit provides the
exclusive dead band in micro seconds so as to avoid the simultaneous firing of two pairs of IGBT’s where one
pair switches off and the other on for a slightest period of time. Hence, the isolator ckt here is associated with
each and every ckt used because it acts as a driver and an isolation to each of the IGBT is provided with one
exclusive transformer supply[3]. The IGBT’s are fired using the appropriate signal using the previous boards
and hence at last a high frequency rectifier ckt with a filtering capacitor is used to get an exact dc
waveform .The basic goal of this particular analysis is to observe the wave forms and characteristics of
converters with differently positioned passive elements in the form of tank circuits.
“Microcontroller Based Substation Monitoring system with gsm modem”.Priya Rachakonda
• The system is used for transmitting the message to predefined number about the
status of electrical parameters such as voltage, current, temperature etc., to improve
the quality of power.
• Studied about the protection, monitoring and control of a power system.
Electrical Engineering is the Branch of Engineering. Electrical Engineering field requires an understanding of core areas including Thermal and Hydraulics Prime Movers, Analog Electronic Circuits, Network Analysis and Synthesis, DC Machines and Transformers, Digital Electronic Circuits, Fundamentals of Power Electronics, Control System Engineering, Engineering Electromagnetics, Microprocessor and Microcontroller. Ekeeda offers Online Mechanical Engineering Courses for all the Subjects as per the Syllabus. Visit : https://ekeeda.com/streamdetails/stream/Electrical-and-Electronics-Engineering
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications.
Similar to Electronics and Communication Engineering (20)
Mechanical Engineering is the Branch of Engineering.The mechanical engineering field requires an understanding of core areas including mechanics, dynamics, thermodynamics, materials science and structural analysis,Fluid Mechanics, Metrology and Instrumentation, Dynamics of Machinery- II, Manufacturing Processes II, Industrial Drafting and Machine Design, Engineering Graphics, Power Plant Engineering. Ekeeda offers Online Mechanical Engineering Courses for all the Subjects as per the Syllabus. Visit us: https://ekeeda.com/streamdetails/stream/mechanical-engineering
Ekeeda Provides Online Video Lectures for Mechanical Engineering Degree Subject Courses for All Engineering Universities. Visit us: https://ekeeda.com/streamdetails/stream/mechanical-engineering
Ekeeda Provides Online Video Lectures for Mechanical Engineering Degree Subject Courses for All Engineering Universities. Visit us: https://ekeeda.com/streamdetails/stream/mechanical-engineering
Civil Engineering is the Branch of Engineering.The Civil engineering field requires an understanding of core areas including Mechanics of Solids, Structural Mechanics - I, Building Construction Materials, Surveying - I, Geology and Geotechnical Engineering, Structural Mechanics, Building Construction, Water Resources and Irrigation, Environmental Engineering, Transportation Engineering, Construction and Project Management. Ekeeda offers Online Mechanical Engineering Courses for all the Subjects as per the Syllabus Visit us: https://ekeeda.com/streamdetails/stream/civil-engineering
Civil Engineering is the Branch of Engineering.The Civil engineering field requires an understanding of core areas including Mechanics of Solids, Structural Mechanics - I, Building Construction Materials, Surveying - I, Geology and Geotechnical Engineering, Structural Mechanics, Building Construction, Water Resources and Irrigation, Environmental Engineering, Transportation Engineering, Construction and Project Management. Ekeeda offers Online Mechanical Engineering Courses for all the Subjects as per the Syllabus Visit us: https://ekeeda.com/streamdetails/stream/civil-engineering
Ekeeda Provides Online Video Lectures for Civil Engineering Degree Subject Courses for All Engineering Universities. Visit us: https://ekeeda.com/streamdetails/stream/civil-engineering
Ekeeda Provides Online Video Lectures for Civil Engineering Degree Subject Courses for All Engineering Universities. Visit us: https://ekeeda.com/streamdetails/stream/civil-engineering
Kinetics of particles impulse momentum methodEkeeda
Ekeeda Provides Online Video Lectures for Civil Engineering Degree Subject Courses for All Engineering Universities. Visit us: https://ekeeda.com/streamdetails/stream/civil-engineering
Learn Online Courses of Subject Introduction to Civil Engineering and Engineering Mechanics. Clear the Concepts of Introduction to Civil Engineering and Engineering Mechanics Through Video Lectures and PDF Notes. Visit us: https://ekeeda.com/streamdetails/subject/introduction-to-civil-engineering-and-engineering-mechanics
Learn Online Courses of Subject Introduction to Civil Engineering and Engineering Mechanics. Clear the Concepts of Introduction to Civil Engineering and Engineering Mechanics Through Video Lectures and PDF Notes. Visit us: https://ekeeda.com/streamdetails/subject/introduction-to-civil-engineering-and-engineering-mechanics
Ekeeda Provides Online Video Lectures for Civil Engineering Degree Subject Courses for All Engineering Universities. Visit us: https://ekeeda.com/streamdetails/stream/civil-engineering
Coplanar forces res & comp of forces - for mergeEkeeda
Ekeeda Provides Online Video Lectures for Civil Engineering Degree Subject Courses for All Engineering Universities. Visit us: https://ekeeda.com/streamdetails/stream/civil-engineering
Ekeeda Provides Online Video Lectures for Civil Engineering Degree Subject Courses for All Engineering Universities. Visit us: https://ekeeda.com/streamdetails/stream/civil-engineering
Ekeeda Provides Online Video Lectures for Civil Engineering Degree Subject Courses for All Engineering Universities. Visit us: https://ekeeda.com/streamdetails/stream/civil-engineering
Infomatica, as it stands today, is a manifestation of our values, toil, and dedication towards imparting knowledge to the pupils of the society. Visit us: http://www.infomaticaacademy.com/
Infomatica, as it stands today, is a manifestation of our values, toil, and dedication towards imparting knowledge to the pupils of the society. Visit us: http://www.infomaticaacademy.com/
Infomatica, as it stands today, is a manifestation of our values, toil, and dedication towards imparting knowledge to the pupils of the society. Visit us/l http://www.infomaticaacademy.com/
Infomatica, as it stands today, is a manifestation of our values, toil, and dedication towards imparting knowledge to the pupils of the society. Visit us: http://www.infomaticaacademy.com/
Infomatica, as it stands today, is a manifestation of our values, toil, and dedication towards imparting knowledge to the pupils of the society. Visit us: http://www.infomaticaacademy.com/
Ekeeda Provides Online Engineering Subjects Video Lectures and Tutorials of Mumbai University (MU) Courses. Visit us: https://ekeeda.com/streamdetails/University/Mumbai-University
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Automobile Management System Project Report.pdfKamal Acharya
The proposed project is developed to manage the automobile in the automobile dealer company. The main module in this project is login, automobile management, customer management, sales, complaints and reports. The first module is the login. The automobile showroom owner should login to the project for usage. The username and password are verified and if it is correct, next form opens. If the username and password are not correct, it shows the error message.
When a customer search for a automobile, if the automobile is available, they will be taken to a page that shows the details of the automobile including automobile name, automobile ID, quantity, price etc. “Automobile Management System” is useful for maintaining automobiles, customers effectively and hence helps for establishing good relation between customer and automobile organization. It contains various customized modules for effectively maintaining automobiles and stock information accurately and safely.
When the automobile is sold to the customer, stock will be reduced automatically. When a new purchase is made, stock will be increased automatically. While selecting automobiles for sale, the proposed software will automatically check for total number of available stock of that particular item, if the total stock of that particular item is less than 5, software will notify the user to purchase the particular item.
Also when the user tries to sale items which are not in stock, the system will prompt the user that the stock is not enough. Customers of this system can search for a automobile; can purchase a automobile easily by selecting fast. On the other hand the stock of automobiles can be maintained perfectly by the automobile shop manager overcoming the drawbacks of existing system.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
COLLEGE BUS MANAGEMENT SYSTEM PROJECT REPORT.pdfKamal Acharya
The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
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Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
Vaccine management system project report documentation..pdfKamal Acharya
The Division of Vaccine and Immunization is facing increasing difficulty monitoring vaccines and other commodities distribution once they have been distributed from the national stores. With the introduction of new vaccines, more challenges have been anticipated with this additions posing serious threat to the already over strained vaccine supply chain system in Kenya.
1. INFOMATICA ACADEMY CONTACT: 9821131002/9029004242
Electronics - II Transistor Amplifier1
Transistor Amplifiers
ANALYSIS OFANAMPLIFIER:
(i) Transistor biasing connections must be correct. Base-Emitter should be in forward
bias and Base-Collector should be in reverse bias.
(ii) Operating point „Q‟ should be adjusted at the center of the load line.
(iii)Operating point should be fixed, it should not shift or change with temperature.
Circuit Description: In the amplifier circuit
1) Transistor is an active device, with amplifies the signal basically by amplifying the
current.
2) Transistor amplifies the signal by drawing current from DC supply (+ ccV ) i.e. energy
is supplied by + ccV .
3) Resistor 1R and 2R provide voltage divider bias to fix the operating point „Q‟ as
shown in the graph
4) Resistor RL is collector load resistor.
5) Resistor RE is connected to stabilize the operating point as explained earlier.
6) Capacitor EC is bypass capacitor, it will bypass AC signal across ER otherwise the
gain of amplifier is reduced.
7) Capacitor C1C and 2CC are coupling capacitors they will couple AC signal and block
DC flow.
MULTISTAGE AMPLIFIER:
When a large gain is required then single stage transistor amplifier is unable to
produce large gain due to limited power dissipation capacity, and distortion may occur
if transistor is driven beyond saturation or below cut off. Therefore multistage amplifier
2. INFOMATICA ACADEMY CONTACT: 9821131002/9029004242
Electronics - II Transistor Amplifier2
is connected; it may be two stage, three-stage amplifier. Fig. shows a three-stage
transistor amplifier and the phase shift at each stage.
The total gain of three-stage amplifier is calculated by a formula.
TotalA = 1 2 3A A A
If Gain (A) of each stage is 100 and suppose input voltage ( inV ) is u1 V then
TotalA = 100 x 100 x 100
= 2
10 x 2
10 x 2
10 TotalA = 6
10
out Total in
6
6 6 6 0
V A V
= 10 1μV
= 10 1 10 1 10 Volt.
Refer fig. each transistor produces 0
180 phase shift then total phase shift of there stage
amplifier is
= 180 + 180 + 180
= 0 0 0 0 0
540 (360 180 )OR (0 180 )
Output signal is 0
180 out of phase with input signal
COUPLING METHODS:
Basically coupling circuit is necessary avoid the shift of operating point, to block
DC reverse current flow, and to couple AC signal. Coupling circuit is designed
according to
(i)Frequency response (ii) Impedance matching (iii) Type of input signal.
There are four methods of amplifier coupling
3. INFOMATICA ACADEMY CONTACT: 9821131002/9029004242
Electronics - II Transistor Amplifier3
(1) R-C coupling
(2) Impedance Coupling
(3) Transformer Coupling
(4) Direct Coupling
Let us see each type with their advantage, disadvantage and typical application.
(1) R-C Coupling:
The Collector load resistor ( CR ) and the Coupling Capacitor ( CC ) form a coupling
circuit as shown in fig (a). This type of coupling is more popular in audio amplifiers;
it couples AC and blocks DC from CCV to base of the transistor as shown in fig (b)
Capacitor coupling you can observe in voltage amplifier of radio receiver i.e. from
volume control to A.F. amplifier.
Frequency Response Of R-C Coupling:
The frequency response of RC coupled amplifier is shown by fig. It also shows the
experimental set up for this purpose. Frequency response tells us about the
performance of a circuit against frequency variation from low to high. Frequency
response is essential because it gives an idea about the range of frequency for which
this coupling is suitable.
The graph of output or the gain of amplifier verses frequency is known as frequency
response. A signal generator is connected to apply various frequencies with small
and constant input voltage to a RC coupled amplifier. The output is measured either
on CRO or VTVM and graph is plotted. The curve shows 3 db curve it falls below 1F
and 2F .
4. INFOMATICA ACADEMY CONTACT: 9821131002/9029004242
Electronics - II Transistor Amplifier4
The frequency response is flat from Z50H to Z20KHL but it is poor below Z50H
above Z20 KH . The gain of amplifier is falling below Z50H and above Z20KHL . This
curve can be explained as follows.
(i) At lower frequencies below Z50H reactance of coupling capacitor ( CC ) is high
because it is given by
C
1
X
2 fC
Therefore, more voltage drop takes place across it, which reduces the input thus
output is poor. Similarly emitter bypass capacitor EC is less effective at these
frequencies.
(ii) Above Z,20 KH the coupling capacitor behaves as a short circuit because its
reactance is negligible which increases the loading effect on the next stage.
Similarly inter-electrode capacitance from collector to base becomes effective its
equivalent capacitive reactance is low which gives negative feedback and it
affects the gain of amplifier.
Advantages:
(i) RC coupled amplifier is suitable only for audio frequency signal Z20H to Z20KH .
(ii) Soldering of RC is convenient and cost of the coupling network is least expensive.
(iii) It is useful in record players, sound section of amplifiers etc.
Disadvantages:
(i) It is not useful for RF signal.
(ii) Impedance matching is poor.
(2) Impedance Coupling:
In RC coupling a power loss ( 2
I R ) takes place across load resistance CR . An inductor
can replace this resistance. Inductor has got high impedance for high frequency.
Therefore large output AC Voltage can be developed across it and since its DC
resistance is very low, DC loss is negligible. This type of coupling is not suitable for
low frequencies it is useful for the high frequencies (RF) above Z20 KH . Impedance
coupling is used in oscillators circuits.
Disadvantages:-
Inductors or RF chokes are expensive and their impedance decreases at low
frequencies. The size of the inductor is also another drawback.
5. INFOMATICA ACADEMY CONTACT: 9821131002/9029004242
Electronics - II Transistor Amplifier5
(3) Transformer Coupling:
Transformer coupling is also popular line RC coupling. In radio receivers
transformer coupling is always used in IF amplifiers connecting one IF amplifier to
the second IF amplifier of radio receiver. Transformer coupling serves three
important purposes.
(i) Output impedance of one stage matching with input impedance of the next stage.
(ii) It provides isolation from one stage to next stage because there is no direct
connection between primary and secondary winding of the transformer.
(iii) Output voltage of one stage can be stepped up with a step up transformer.
Transformer coupling also commonly used in RF amplifiers of radio and TV circuits.
Fig. shows that load resistance CR is replaced by primary of transformer there is no
capacitance from secondary to input of the next stage. DC isolation is achieved with
secondary winding itself because DC cannot be transformed from primary to
secondary.
Transformer coupling with shunt capacitor across it is another way of coupling in
amplifier. Such type of amplifier is known as “tuned-RF/(TRF)” amplifier. Here L-C
parallel resonance principle is used which is tuned to desired frequency so the
impedance of L-C circuit becomes maximum only at resonant frequency.
Advantages:
1) This type of coupling is suitable for RF frequencies, as in radio circuits to amplify
station signals from Z550 KH to Z1600 KH medium wave band.
2) Transformer coupling provides good impedance matching and better gain.
3) Power loss across collector load is minimized up to negligible value.
Disadvantages:
1) It has poor frequency response i.e. the gain varies with frequency.
2) The size of the transformer and its high cost.
3) Amount of „hum‟ or noise is comparatively high.
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(4) Direct Coupling:
In this method there is no coupling component, the collector of one transistor is
directly connected to the base of the next transistor. These types of amplifiers are
used in DC amplification or amplification of very low frequencies below 10Hz. For
example, to drive an active load like DC relay, DC motor, headphones, etc. the main
drawback of such amplifier is, temperature effect It is called as temperature drift it
affects the biasing of transistor.
Fig. shows an example of direct coupling. When light falls on LDR is resistance
decreases therefore more DC voltage is developed across the base resistance BR .
This change in base voltage is amplified in the collector, which drives the next
transistor the collector goes low. The low collector voltage of the first transistor is
applied to the base of second transistor. The low base voltage will make the second
transistor OFF. Thus relay is operated in OFF state. When light is made cut-off the
base voltage decreases which is amplified by the first transistor. Its collector goes
high which is coupled to the second transistor. It will make the second transistor
ON and thus relay is operated into ON state. In this way it couples and amplifies
DC signal.
Advantages:
i) The coupling circuit is simple because it requires minimum resistors.
ii)It is a low cost method because no coupling component is required.
Disadvantages:
i) It is not useful for AC high frequency signal.
ii)Operating point is shifted due to temperature.
POWER AMPLIFIERS:
Power amplification is necessary because the output stage of any instrument required
to be more powerful. It should supply maximum current and maximum voltage (I x V =
Power). Fig. shows the block diagram of an amplifier stage.
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The output of voltage amplifier is not capable of driving the loudspeaker because of
heavy load current. Similarly in radio transmitter, TV transmitter circuit, the output of
amplifier is not capable of driving the antenna. Therefore a power amplifier is required
to deliver maximum current with maximum voltage to drive the loudspeaker, antenna
etc.
They are classified into four different types
i) Class A ii) Class AB iii) Class B iv) Class C
i) Class A power Amplifier:
The Class A power amplifier is operated at the center of the load line, as it is
illustrated in fig. the operating point „Q‟ is located at the center of load line.
Advantages:
The output of Class A amplifier is undistorted and full cycle of input signal is
amplified. Transistor conducts for 360⁰ i.e., it amplifies complete input signal. The
transistor is operated in active region.
Disadvantage:
Refer the fig. at zero signal condition, when input signal is zero or when input signal
is absent collector current of 100 mA flows through transistor and CEV (on X-axis) it is
8V therefore power loss across the transistor is lossP =8V×100mA=800mW The efficiency
of class A amplifier is only 25%, it is poor efficiency.
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ii)Class B power Amplifier:
In class B power amplifier transistor is biased at cut off as illustrated in fig. The
operating point is adjusted at cut off. The result of this, under zero signal condition
transistors is in cut off therefore less wastage of power takes place under zero signal
condition.
Advantage:-
Since, only half cycle is amplified as shown, during the negative half cycle of input
signal, transistor remains cut off but the efficiency increases about 78.5% because
when signal is zero transistor is OFF. Current through transistor is zero.
Disadvantage:
Since, the transistor is biased at cut off it conducts only for positive half cycle of input
signal. It remains cut off for negative half cycle as shown. The transistor amplifies
only half cycle and thus extremely high distortion is produced. There is a crossover
distortion.
Class B Push Pull Amplifier:-
The fig. shows a typical Push Pull Class B amplifier. In Positive half cycle transistor 1T
is ON for 180⁰ and current flows through output transformer. Similarly in negative half
cycle transistor 2T is ON and 1T is cut off it also flows through output transformer and
thus in the secondary side a amplified output is developed.
Push Pull arrangement eliminates much of the distortion but at the midpoint of two
half cycles a distortion occur known as Crossover distortion.
This crossover distortion is produced because of nonlinear characteristics of internal
diode of the transistor at and below 0.6 volt.
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iii) Class AB Power Amplifier:
It is the solution to avoid crossover distortion of class B amplifier. It‟s
characteristics lies between class A and class B amplifier. It‟s operating point is
located slightly above cut off as shown in fig., it is in between class A and Class B.
Transistor in class AB conducts more than 180⁰ angle and less than 360⁰. The
efficiency of class AB is more than class A and less than Class B push full amplifier,
commonly used in radio circuit to drive the load speaker.
iv) Class C Power Amplifier:
In this class, transistor is conducting less than 180⁰. It‟s operating point lies
beyond cut off.
Advantages:
Since transistor is operated for less than 180⁰ efficiency is very high about 100%. It is
used in tuned amplifiers and in oscillators.
Disadvantage:
Extremely high distortion hence it is not useful for audio amplification. It is used in
oscillator circuits.
COMPARISON:-
Class A Class B Class AB Class C
Operating
point Q located
At the center At cutoff Before Cutoff Beyond cutoff
Transistor
conducts for
360⁰ 180⁰ More than 180⁰ Less than 180⁰
Distortion Absent Crossover Less than 50% Highest
Efficiency Lowest Better Better Excellent
Application Voltage amplifier Push-pull
amplifier
Push-pull
amplifier
Oscillators
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DIFFERENTIAL AMPLIFIER:-
It is a special type of amplifier capable of amplifying the difference hence called as
difference amplifier or differential amplifier.
It plays very important role in “operational amplifier commonly known as “OPAMP”. It
is also useful in other industrial circuits.
The fig. shows the circuit diagram of differential amplifier, it is a symmetrical structure
in which two identical transistors are connected with equal collector resistors.
The differential amplifier has two inputs:-
(i) Inverting input and
(ii) Non-inverting input.
The basic difference between these two is inverting input produces output 180⁰ out of
phase with input while non-inverting does not produce phase shift between input and
output.
It has two inputs 1V and 2V the output is taken either between two collectors or from
one collector with respect to ground. The fig. (3.14) shows most practical and widely
used configuration, output is taken from collector of 1T with respect to ground.
Differential amplifier it can be operated in different modes such as:-
1) Differential input mode
2) Common input mode
3) Single ended input mode
1) Differential input mode:
In this mode signal is applied between terminal 1V and 2V and output is taken from
the collector. It is called as differential input single ended output mode.
As shown in figure (3.14) output is taken from either of collectors. Its output voltage
is given by equation –
0 1 2V =A V -V
Since. 1V is 180⁰ output of phase with 2V but equal in amplitude.
0 1 2 1V =A V -V =2AV
Thus, in differential mode maximum gain is obtained, twice input voltage multiplied
by gain (A).
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2) Common input mode:
In this mode same signal is applied to both input terminals that is
1 2
0 1 2
1 1
V =V then
V =A V -V
=A V -V
=0 it means that for common signals like noise its gain is zero it rejects unwanted noise signals
DM
CM
A Differentialmodegain
CMRR = =
A Common modegain
3) Single ended input mode:
In this mode, input is applied to one of the inputs and other input is grounded,
output can be differential or it can be single ended. When output is single ended it is
called as an OP-AMP. In OP-AMP the mode is single ended input single ended output
or differential input, single ended output.
TRANSISTOR AS A SWITCH:-
Normally transistor is used as an amplifier where it is operated below saturation and
above cut off; it is operated in active region. Another important application of transistor
in digital circuits, it can be operated as a switch. In switching application the transistor
is operated either is saturation or in cut off only and non in active region. It has got
following advantages over normal mechanical switch.
i) Low cost ii) Small size iii) High speed
Let us see how transistor is used as a switch.
Fig. shows a NPN transistor with emitter grounded. Input voltage is applied to the base
terminal and output is taken from collector ( CEV ). Here transistor is operated either in
saturation or in cut off instead of active region.
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SOLVED PROBLEMS
1) What is the value of collector load resistance required to set CV as 4 volts and CI as
1mA for the collector supply voltage of 6 volts in Transistor Amplifier.
CC C C C
CE CC C C
C C CC C
CC C
C
C
-3
3
C
Solution: Given V =6 V, I =1mA R = ? V = 4V
Formula for collector voltageV = V -I R
I R = V - V
V - V
R =
I
6-4
=
1×10
R = 2×10 Ω= 2KΩCollector load should be 2KΩ
2) Find the total voltage gain of a three – stage amplifier in db if first stage has gain of
100 second has 300 and third has 400.
o
i
o
i
o
i
V
Solution: i) First Stage Voltage Gain in db = 20log db
V
= 20log100= 20×2= 40db
V
ii)Second Stage Voltage Gain in db = 20log db
V
= 20log300= 20×2.48= 49.6db
V
iii)ThirdStageVoltageGainin db= 20log db
V
= 20log 400= 20×2.60=52db
Total gain = 40+49.6+52=141db