The study of the basics of electronics can be studied through the link http://bit.ly/2PPv0mv
The transistor is a semiconductor device with three connections, capable of amplification in addition to rectification
This presentation contains the basic information you need to know about operational amplifier.
I have tried to cover all the basic info. If anything is left out or you have any suggestions i will appreciate it.
ENT201-Electronic DevicesLecture No. 10Unit-1 *Quantitative Theory of the PN-Diode Currents- Diode Current Equation.
Milliman's Electronic Devices and Circuits
The attached narrated power point presentation explains the construction, working and applications of PN Junction Diodes. The material will be useful for KTU first year students who prepare for the subject EST 130, Part B, Basic Electronics Engineering.
The study of the basics of electronics can be studied through the link http://bit.ly/2PPv0mv
The transistor is a semiconductor device with three connections, capable of amplification in addition to rectification
This presentation contains the basic information you need to know about operational amplifier.
I have tried to cover all the basic info. If anything is left out or you have any suggestions i will appreciate it.
ENT201-Electronic DevicesLecture No. 10Unit-1 *Quantitative Theory of the PN-Diode Currents- Diode Current Equation.
Milliman's Electronic Devices and Circuits
The attached narrated power point presentation explains the construction, working and applications of PN Junction Diodes. The material will be useful for KTU first year students who prepare for the subject EST 130, Part B, Basic Electronics Engineering.
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
The following presentation is a part of the level 4 module -- Electrical and Electronic Principles. This resources is a part of the 2009/2010 Engineering (foundation degree, BEng and HN) courses from University of Wales Newport (course codes H101, H691, H620, HH37 and 001H). This resource is a part of the core modules for the full time 1st year undergraduate programme.
The BEng & Foundation Degrees and HNC/D in Engineering are designed to meet the needs of employers by placing the emphasis on the theoretical, practical and vocational aspects of engineering within the workplace and beyond. Engineering is becoming more high profile, and therefore more in demand as a skill set, in today’s high-tech world. This course has been designed to provide you with knowledge, skills and practical experience encountered in everyday engineering environments.
SEMICONDUCTOR DEVICES AND APPLICATIONS.
Introduction to P-N Junction Diode and V-I Characteristics
Half wave and Full wave rectifiers
Capacitor filters
Zener diode and its Characteristics
Zener Diode as Voltage regulator
BJT small signal model – Analysis of CE, CB, CC amplifiers- Gain and frequency response – MOSFET small signal model– Analysis of CS and Source follower – Gain and frequency response- High frequency analysis.
Orbits : types of satellites : frequency used link establishment, MA techniques used in satellite communication, earth station; aperture actuators used in satellite – Intelsat and Insat: fibers – types:
sources, detectors used, digital filters, optical link: power line carrier communications: SCADA
AM – Frequency spectrum – vector representation – power relations – generation of AM – DSB, DSB/SC, SSB, VSB AM Transmitter & Receiver; FM and PM – frequency spectrum – power relations : NBFM & WBFM, Generation of FM and DM, Armstrong method & Reactance modulations : FM & PM frequency.
PN junction diode –structure, operation and V-I characteristics, diffusion and transient capacitance - Rectifiers – Half Wave and Full Wave Rectifier,– Display devices- LED, Laser diodes- Zener diodecharacteristics-Zener Reverse characteristics – Zener as regulator,TRANSISTORS, BJT, JFET, MOSFET- structure, operation, characteristics and Biasing UJT, Thyristor and IGBT Structure and characteristics,BJT small signal model – Analysis of CE, CB, CC amplifiers- Gain and frequency response –
MOSFET small signal model– Analysis of CS and Source follower – Gain and frequency response- High frequency analysis,BIMOS cascade amplifier, Differential amplifier – Common mode and Difference mode analysis – FET input stages – Single tuned amplifiers – Gain and frequency response – Neutralization methods, power amplifiers –Types (Qualitative analysis),Advantages of negative feedback – voltage / current, series , Shunt feedback –positive feedback – Condition for oscillations, phase shift – Wien bridge, Hartley, Colpitts and Crystal oscillators.
Multinational Corporations – Environmental Ethics – Computer Ethics – Weapons Development – Engineers as Managers – Consulting Engineers – Engineers as Expert Witnesses and Advisors – Moral Leadership –Code of Conduct – Corporate Social Responsibility
Safety and Risk – Assessment of Safety and Risk – Risk Benefit Analysis and Reducing Risk - Respect for Authority – Collective Bargaining – Confidentiality – Conflicts of Interest – Occupational Crime – Professional Rights – Employee Rights – Intellectual Property Rights (IPR) – Discrimination
Senses of “Engineering Ethics” – Variety of moral issues – Types of inquiry – Moral dilemmas – Moral Autonomy – Kohlberg‟s theory – Gilligan‟s theory – Consensus and Controversy – Models of professional roles - Theories about right action – Self-interest – Customs and Religion – Uses of Ethical Theories
Morals, values and Ethics – Integrity – Work ethic – Service learning – Civic virtue – Respect for others – Living peacefully – Caring – Sharing – Honesty – Courage – Valuing time – Cooperation – Commitment – Empathy – Self confidence – Character – Spirituality – Introduction to Yoga and meditation for professional excellence and stress management.
Trust models for Grid security environment – Authentication and Authorization methods – Grid security infrastructure – Cloud Infrastructure security: network, host and application level – aspects of data security, provider data and its security, Identity and access management architecture, IAM practices in the cloud, SaaS, PaaS, IaaS availability in the cloud, Key privacy issues in the cloud.
Open source grid middleware packages – Globus Toolkit (GT4) Architecture , Configuration – Usage of Globus – Main components and Programming model - Introduction to Hadoop Framework - Mapreduce, Input splitting, map and reduce functions, specifying input and output parameters, configuring and running a job – Design of Hadoop file system, HDFS concepts, command line and java interface, dataflow of File read & File write.
Cloud deployment models: public, private, hybrid, community – Categories of cloud computing: Everything as a service: Infrastructure, platform, software - Pros and Cons of cloud computing – Implementation levels of virtualization – virtualization structure – virtualization of CPU, Memory and I/O devices – virtual clusters and Resource Management – Virtualization for data center automation.
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Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
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Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
1. EC8353 ELECTRONIC DEVICES AND CIRCUITS
Unit 1
Dr Gnanasekaran Thangavel
Professor and Head
Electronics and Instrumentation
Engineering
R M K Engineering College
3. Classification
7/11/2018Dr Gnanasekaran Thangavel3
Active components
Rely on a source of energy and can inject power into a circuit
Passive components
Can't introduce net energy into the circuit and can't rely on a
source of power
Electromechanical
can carry out electrical operations by using moving parts or by
using electrical connections
6. Electromechanical
7/11/2018Dr Gnanasekaran Thangavel6
Passive components that use piezoelectric effect:
Components that use the effect to generate or filter high frequencies
Crystal – a ceramic crystal used to generate precise frequencies (See
the Modules class below for complete oscillators)
Ceramic resonator – Is a ceramic crystal used to generate semi-
precise frequencies
Ceramic filter – Is a ceramic crystal used to filter a band of
frequencies such as in radio receivers
Surface acoustic wave (SAW) filters
Components that use the effect as mechanical transducers.
Ultrasonic motor – Electric motor that uses the piezoelectric effects
For piezo buzzers and microphones,
7. UNIT I PN JUNCTION DEVICES
PN junction diode –structure, operation and V-I
characteristics, diffusion and transient capacitance -
Rectifiers – Half Wave and Full Wave Rectifier,– Display
devices- LED, Laser diodes- Zener diode characteristics-
Zener Reverse characteristics – Zener as regulator
7 Dr Gnanasekaran Thangavel 7/11/2018
1. https://www.youtube.com/watch?v=OyC02DWq3mI
2. https://www.youtube.com/watch?v=d4zO39K_ce8
3. https://www.youtube.com/watch?v=AspBbh_jOuk
4. https://www.youtube.com/watch?v=UMgOG4OqBT0
5. https://www.youtube.com/watch?v=Kl8IOESVWlM
8. PN junction diode
Definition
“A semiconductor device with two terminals, typically
allowing the flow of current in one direction only.
“A diode is a specialized electronic component with two
electrodes called the anode and the cathode. They are
made with semiconductor materials such as silicon,
germanium, or selenium. The fundamental property of a
diode is its tendency to conduct electric current in only
one direction.”
“A Diode is an electronic device that allows current to flow
in one direction only. It is a semiconductor that consists of
a p-n junction. They are used most commonly to convert8 Dr Gnanasekaran Thangavel 7/11/2018
9. Semiconductors and Physical Operation of
Diodes
Semiconductors
Doping
• n-type material
• p-type material
pn-Junctions
• forward, reverse, breakdown
• solar cells, LEDs, capacitance
11. The Silicon Atom
Nucleus:
14 protons
14 neutrons
10 core electrons:
1s22s22p6
-
-
-
-
4 valence
electrons
The 4 valence electrons are responsible
for forming covalent bonds
12. Silicon Crystal
Each Si atom has four nearest neighbors — one for each valence electron
0.5 nm
13. Two-dimensional Picture of Si
note: each line ( —) represents a valence electron
covalent bond
At T=0 Kelvin, all of
the valence electrons
are participating in
covalent bonds
There are no “free”
electrons, therefore no
current can flow in the
silicon INSULATOR
Si
14. Silicon at Room Temperature
For T>0 K, the silicon atoms
vibrate in the lattice. This is
what we humans sense as
“heat.”
Occasionally, the vibrations
cause a covalent bond to break
and a valence electron is free
to move about the silicon.
15. Silicon at Room Temperature
-
-
For T>0 K, the silicon atoms
vibrate in the lattice. This is
what we humans sense as
“heat.”
Occasionally, the vibrations
cause a covalent bond to break
and a valence electron is free
to move about the silicon.
= free electron
16. Silicon at Room Temperature
The broken covalent bond site
is now missing an electron.
This is called a “hole”
The hole is a missing negative
charge and has a charge of +1.
= a hole
-
+
hole
17. Current Flow in Silicon
*
+ -
+-
a bar of silicon
I
V
Bond breaking
due to:
-heat (phonons)
-light (photons)
Conductance is
proportional to
the number of
electrons and
holes:
Si resistance
depends on temp.
and light
18. Some important facts
The number of electrons = the number of holes
that is, n = p in pure silicon
this is called intrinsic material
High temp more electrons/holes lower resistance
Very few electrons/holes at room temperature
n=1.5x1010 per cm3, but nSi = 5x1022 per cm3
n/nSi = 3x10-13 (less than 1 in a trillion Si bonds are broken
This is a SEMICONDUCTOR
19. Important Facts (cont.)
Band Gap: energy required to break a covalent bond and free
an electron
Eg = 0.66 eV (germanium)
Eg = 1.12 eV (silicon)
Eg = 3.36 eV (gallium nitride)
Metals have Eg= 0
very large number of free electrons high conductance
Insulators have Eg > 5 eV
almost NO free electrons zero conductance
20. Doping
Intentionally adding impurities to a semiconductor to create
more free electrons OR more holes (extrinsic material)
n-type material
more electrons than holes (n>p)
p-type material
more holes than electrons (p>n)
HOW???
22. n-type silicon
add atoms from column V of the periodic table
Si
P
-
Column V elements have 5 valence
electrons
Four of the electrons form covalent bonds
with Si, but the 5th electron is unpaired.
Because the 5th electron is weakly bound,
it almost always breaks away from the P
atom
This is now a free electron.
23. VERY IMPORTANT POINT
Si
P+
-
The phosphorus atom has donated an
electron to the semiconductor (Column V
atoms are called donors)
The phosphorus is missing one of its
electrons, so it has a positive charge (+1)
The phosphorus ion is bound to the
silicon, so this +1 charge can’t move!
The number of electrons is equal to
the number of phos. atoms: n = Nd
25. p-type silicon
add atoms from column III of the periodic table
Si
B
Column III elements have 3 valence electrons
that form covalent bonds with Si, but the 4th
electron is needed.
This 4th electron is taken from the nearby
Si=Si bond
26. p-type silicon
add atoms from column III of the periodic table
Si
B
Column III elements have 3 valence electrons
that form covalent bonds with Si, but the 4th
electron is needed.
This 4th electron is taken from the nearby
Si=Si bond
This “stolen” electron creates a free hole.
hole
27. VERY IMPORTANT POINT
Si
B-
+
The boron atom has accepted an electron
from the semiconductor (Column III
atoms are called acceptors)
The boron has one extra electron, so it
has a negative charge (-1)
The boron ion is bound to the silicon, so
this -1 charge can’t move!
The number of holes is equal to
the number of boron atoms: p = Na
28. The pn Junction
p-type n-type
anode cathode
integrated circuit diode
metal
silicon oxide
doped silicon
wafer (chip)
29. Dopant distribution inside a
pn junction
p>>n n>>p
excess electrons diffuse
to the p-type region
excess holes diffuse
to the n-type region
30. n~0, and donor ions are
exposed
Dopant distribution inside a
pn junction
excess electrons diffuse
to the p-type region
excess holes diffuse
to the n-type region
DEPLETION REGION:
+
p~0, and acceptor ions are
exposed
p>>n n>>p
+
+
+-
-
-
-
31. Voltage in a pn junction
p>>n n>>p
+
+
+-
-
-
-
x
charge, r(x)
x
x
electric field,
E(x)
voltage,
V(x)
+
~0.7 volts
(for Si)
x
dxxxE
0
)(
1
)( r
x
dxxExV
0
)()(
32. Zero Bias
p>>n n>>p
+
+
+-
-
-
x
voltage,
V(x)
~0.7 volts
(for Si)
At zero bias (vD=0), very few electrons or holes can overcome this built-in
voltage barrier of ~ 0.7 volts (and exactly balanced by diffusion)
iD = 0
34. Reverse Bias
p>>n n>>p
+
+
+-
-
-
x
voltage,
V(x)
-5 volts
As the bias (vD) becomes negative, the barrier becomes larger. Only
electrons and holes due to broken bonds contribute to the diode
current. iD = -Is
vD
0.0 volts
1/2Is
1/2Is
Is
35. Breakdown
p>>n n>>p
+
+
+-
-
-
x
voltage,
V(x)
-50 volts
As the bias (vD) becomes very negative, the barrier becomes larger.
Free electrons and holes due to broken bonds are accelerated to
high energy (>Eg) and break other covalent bonds – generating
more electrons and holes (avalanche).
vD
0.0 volts
|I| >> Is
large reverse current
36. Solar Cell (Photovoltaic)
p>>n n>>p
+
+
+-
-
-
x
voltage,
V(x)
~0.7 volts
(for Si)
Light hitting the depletion region causes a covalent bond to break.
The free electron and hole are pushed out of the depletion region
by the built-in potential (0.7v).
Rload
light
Iph
37. Light Emitting Diode (LED)
7/11/2018Dr Gnanasekaran Thangavel37
A light-emitting diode (LED) is a two-lead semiconductor light
source. It is a p–n junction diode that emits light when activated.
When a suitable voltage is applied to the leads, electrons are able to
recombine with electron holes within the device, releasing energy in
the form of photons. This effect is called electroluminescence, and
the colour of the light (corresponding to the energy of the photon) is
determined by the energy band gap of the semiconductor.
38. Light Emitting Diode (LED)
p>>n n>>p
+
+
+-
-
-
x
voltage,
V(x)
2.0 volts
In forward bias, an electron and hole collide and self-annihilate in the
depletion region. A photon with the gap energy is emitted. Only occurs
in some materials (not silicon).
vD
1.5 volts
0.0 volts
photon
40. Junction Capacitance (Cj)
The junction capacitance must be charged and discharged
every time the diode is turned on and off
Transistors are made of pn junctions. The capacitance due
to these junctions limits the high frequency performance of
transistors remember, Zc = 1/jwC becomes a short circuit
at high frequencies (Zc 0) this means that a pn junction
looks like a short at high frequency
This is a fundamental principle that limits the performance
of all electronic devices
41. HALF WAVE RECTIFIER
The Half wave rectifier is a circuit, which
converts an ac voltage to dc voltage.
The primary of the transformer is
connected to ac supply. This induces an
ac voltage across the secondary of the
transformer.
During the positive half cycle of the input
voltage the polarity of the voltage across
the secondary forward biases the diode.
As a result a current IL flows through the
load resistor, RL. The forward biased
diode offers a very low resistance and
hence the voltage drop across it is very
small. Thus the voltage appearing across
the load is practically the same as the
42. HALF WAVE RECTIFIER …….
7/11/2018Dr Gnanasekaran Thangavel42
During the negative half cycle of the input voltage the polarity of
the secondary voltage gets reversed. As a result, the diode is
reverse biased.
Practically no current flows through the circuit and almost no
voltage is developed across the resistor. All input voltage
appears across the diode itself.
Hence we conclude that when the input voltage is going through
its positive half cycle, output voltage is almost the same as the
input voltage and during the negative half cycle no voltage is
available across the load. This explains the unidirectional
pulsating dc waveform obtained as output. The process of
removing one half the input signal to establish a dc level is aptly
44. FULL WAVE RECTIFIER
• A Full Wave Rectifier is a circuit, which converts an ac voltage into
a pulsating dc voltage using both half cycles of the applied ac
voltage. It uses two diodes of which one conducts during one half
cycle while the other conducts during the other half cycle of the
applied ac voltage.
46. Positive cycle, D2 off, D1 conducts;
Vo – Vs + V = 0
Vo = Vs - V
Full-Wave Rectification – circuit with center-
tapped transformer
Since a rectified output voltage occurs during both positive and
negative cycles of the input signal, this circuit is called a full-
wave rectifier.
Also notice that the polarity of the output voltage for both
cycles is the same
Negative cycle, D1 off, D2 conducts;
Vo – Vs + V = 0
Vo = Vs - V
47. Vs = Vpsin t
V
-V
Notice again that the peak voltage of Vo is lower since Vo = Vs -
V
Vp
• Vs < V, diode off, open circuit, no current flow,Vo = 0V
48. Positive cycle, D1 and D2 conducts, D3 and D4 off;
+ V + Vo + V – Vs = 0
Vo = Vs - 2V
Full-Wave Rectification –Bridge Rectifier
Negative cycle, D3 and D4 conducts, D1 and D2 off
+ V + Vo + V – Vs = 0
Vo = Vs - 2V
Also notice that the polarity of the output voltage for both cycles is the same
49. A full-wave center-tapped rectifier circuit is shown in Fig. 3.1. Assume that for each diode,
the cut-in voltage, V = 0.6V and the diode forward resistance, rf is 15. The load
resistor, R = 95 . Determine:
peak output voltage, Vo across the load, R
Sketch the output voltage, Vo and label its peak value.
25: 1
125 V (peak
voltage)
( sine wave )
50. SOLUTION
peak output voltage, Vo
Vs (peak) = 125 / 25 = 5V
V +ID(15) + ID (95) - Vs(peak) = 0 ID = (5 – 0.6) / 110
= 0.04 A Vo (peak) = 95 x 0.04 = 3.8V
3.8V
Vo
t
51. Duty Cycle: The fraction of the wave cycle over which the
diode is conducting.
52. EXAMPLE 3.1 – Half Wave Rectifier
Determine the currents and voltages of the half-wave rectifier circuit. Consider the half-wave rectifier circuit
shown in Figure.
Assume and . Also assume that
Determine the peak diode current, maximum reverse-bias diode voltage, the fraction of the wave cycle over
which the diode is conducting.
A simple half-wave battery charger circuit
-VR + VB + 18.6 = 0
VR = 24.6 V
- VR +
+
-
53.
54. The peak inverse voltage (PIV) of the diode is the
peak value of the voltage that a diode can withstand
when it is reversed biased
55. Type of
Rectifier
PIV
Half Wave Peak value of the input secondary voltage, Vs (peak)
Full Wave :
Center-Tapped
2Vs(peak) - V
Full Wave: Bridge Vs(peak)- V
56. Example: Half Wave Rectifier
Given a half wave rectifier with input primary voltage, Vp = 80 sin t and the
transformer turns ratio, N1/N2 = 6. If the diode is ideal diode, (V = 0V), determine the
value of the peak inverse voltage.
1. Get the input of the secondary voltage:
80 / 6 = 13.33 V
1. PIV for half-wave = Peak value of the input voltage = 13.33 V
57. EXAMPLE 3.2
Calculate the transformer turns ratio and the PIV voltages for each type of the full wave rectifier
a) center-tapped
b) bridge
Assume the input voltage of the transformer is 220 V (rms), 50 Hz from ac main line source. The desired peak
output voltage is 9 volt; also assume diodes cut-in voltage = 0.6 V.
58. Solution: For the centre-tapped transformer circuit the peak voltage of the transformer secondary
is required
The peak output voltage = 9V
Output voltage, Vo = Vs - V
Hence, Vs = 9 + 0.6 = 9.6V
Peak value = Vrms x 2
So, Vs (rms) = 9.6 / 2 = 6.79 V
The turns ratio of the primary to each secondary winding is
The PIV of each diode: 2Vs(peak) - V = 2(9.6) - 0.6 = 19.6 - 0.6 = 18.6 V
59. Solution: For the bridge transformer circuit the peak voltage of the transformer secondary is
required
The peak output voltage = 9V
Output voltage, Vo = Vs - 2V
Hence, Vs = 9 + 1.2 = 10.2 V
Peak value = Vrms x 2
So, Vs (rms) = 10.2 / 2 = 7.21 V
The turns ratio of the primary to each secondary winding is
The PIV of each diode: Vs(peak)- V = 10.2 - 0.6 = 9.6 V
60. Laser diodes
7/11/2018Dr Gnanasekaran Thangavel60
LASER — Light Amplification by Stimulated Emission of Radiation
The Laser is a source of highly directional, monochromatic, coherent light.
The Laser operates under a “stimulated emission” process.
The semiconductor laser differs from other lasers (solid, gas, and liquid lasers):
small size (typical on the order of 0.1 × 0.1 × 0.3 mm3)
high efficiency
the laser output is easily modulated at high frequency by controlling the junction current
low or medium power (as compared with ruby or CO2 laser, but is comparable to the He-Ne
laser)
particularly suitable for fiber optic communication
Important applications of the semiconductor lasers:
optical-fiber communication, video recording, optical reading, high-speed laser printing.
high-resolution gas spectroscopy, atmospheric pollution monitoring.
61. 61
Comparison between an LD and LED
Laser Diode
Stimulated radiation
narrow line width
coherent
higher output power
a threshold device
strong temperature dependence
higher coupling efficiency to a fiber
LED
Spontaneous radiation
broad spectral
incoherent
lower output power
no threshold current
weak temperature dependence
lower coupling efficiency
62. Laser Diode Construction
7/11/2018Dr Gnanasekaran Thangavel62
The figure shows a simplified
construction of a laser diode, which is
similar to a light emitting diode (LED).
It uses gallium arsenide doped with
elements such as selenium, aluminum,
or silicon to produce P type and N type
semiconductor materials.
While a laser diode has an additional
active layer of undoped (intrinsic)
gallium arsenide have the thickness
only a few nanometers, sandwiched
between the P and N layers, effectively
creating a PIN diode (P type-Intrinsic-N
type). It is in this layer that the laser
light is produced.
63. How Laser Diode Work?
7/11/2018Dr Gnanasekaran Thangavel63
Every atom according to the quantum
theory, can energies only within a certain
discrete energy level. Normally, the atoms
are in the lowest energy state or ground
state.
When an energy source given to the atoms
in the ground state can be excited to go to
one of the higher levels. This process is
called absorption.
After staying at that level for a very short
duration, the atom returns to its initial
ground state, emitting a photon in the
process, This process is called
spontaneous emission.
These two processes, absorption and
64. How Laser Diode Work?
7/11/2018Dr Gnanasekaran Thangavel64
In case the atom, still in an excited state, is struck by an outside photon having
precisely the energy necessary for spontaneous emission, the outside photon is
increased by the one given up by the excited atom, Moreover, both the photons
are released from the same excited state in the same phase, This process, called
stimulated emission, is fundamental for laser action (shown in above figure).
In this process, the key is the photon having exactly the same wavelength as that
of the light to be emitted.
Amplification and Population Inversion
When favorable conditions are created for the stimulated emission, more and more
atoms are forced to emit photons thereby initiating a chain reaction and releasing
an enormous amount of energy.
This results in a rapid build up of energy of emitting one particular wavelength
(monochromatic light), travelling coherently in a particular, fixed direction. This
process is called amplification by stimulated emission.
65. Laser Diode
Laser diode is an improved LED, in the sense that uses stimulated emission in semiconductor from
optical transitions between distribution energy states of the valence and conduction bands with
optical resonator structure such as Fabry-Perot resonator with both optical and carrier
confinements.
66. Laser Diode Characteristics
Nanosecond & even picoseconds response time (GHz BW)
Spectral width of the order of nm or less
High output power (tens of mW)
Narrow beam (good coupling to single mode fibers)
Laser diodes have three distinct radiation modes namely,
longitudinal, lateral and transverse modes.
In laser diodes, end mirrors provide strong optical feedback in
longitudinal direction, so by roughening the edges and cleaving
the facets, the radiation can be achieved in longitudinal
direction rather than lateral direction.
67. Zener Diode
A Zener diode is a type of diode that permits current not only in
the forward direction like a normal diode, but also in the reverse
direction if the voltage is larger than the breakdown voltage
known as "Zener knee voltage" or "Zener voltage".