Arab Academy for Science ,
Technology and Maritime
Transport
Electronics Engineering
EC 237
Dr. Mohamed Hassan
Course Assessment
• * In-class exams:
•
7th week exam
•
12th week exam
40%
25%
15%
• *Tutorial exams and activities: 10%
• (5%with 7th week exam + 5%with 12th week exam)
•
• * All term activity : 10% (with final)
• Progress within term (and –or), Absence in Lecs & Secs (and-or),
Bonuses in Lecs only,
• Dr. evaluation (and-or) and Extra projects-research.
• Final exam:
40%
Rules and educational hints (very important)
• You can view your marks and answer book in all exams any time according
to model answer (viewed in Dr or TAs office hours).
•
25% of any sheet will not be solved intentionally ….they will left for your
home works OR class activities OR exams in sections OR exams of 7th and
12th.
• You have all wrights to ask about the 25% of previous point in TAs office
hours and not in the day of exam and get the true solution but in condition
of trying and working before asking.
• We will construct list contains each student name, Id and email for each
class. Each student will be responsible for checking his mail 2 times a week
during the term for any upgrades related to our subject.
• Dr is not responsible for error mail- junk- or not giving mails. Dr will send
material to each class and contact specific student if any matter happens
during the term.
• Any problem just contact Dr. mhabdazeem@hotmail.com
•
Room 308A
• Bonus marks are allowed through good participation in lectures and good
outside projects.
• Students that have lower than 26/50 by end of week 14 will be advised to
make (w). (Dr. will send advise through the mail by end of week 14).
• You have to get the lectures with you each time (printed or on PDAs) to
follow up.
• You have to be prepared for tutorials activities each time (calculatorpapers-pen……
TEXT BOOKS:
• C.J.Savant, M.S.Rooden, G.L.Carpenter, ”Electronic Design”,
Addison Wesley
• Martin Rodan and Gordon Carpenter, " Electronic Design: from
concept to reality“
REFERENCE BOOKS:
• Sedra & Smith, Microelectronic Circuits, 5th edition, 2004.
• Boylestad, Nashelsky, Electronic Devices&circuit theory, Prentice
Hall, 2005
Course Contents
•Semiconductor Physics:
Studying semiconductors materials, Extrinsic materials and
semiconductor diodes.
• P-N junction diode:
Theory of operation, Built-in potential, Forward and reverse
connections, P-N junction as a circuit element, special diods
and P-N junction diode Applications.
• BJT and MOSFET:
Bipolar Junction Transistor (BJT) and Field Effect Transistor
(FET) Electronic amplifiers and switches
Materials Types
1. INSULATORS
• An INSULATOR is any material that inhibits
(stops) the flow of electrons (electricity).
• An insulator is any material with 5 to 8 free
electrons in the outer ring. Because, atoms
with 5 to 8 electrons in the outer ring are held
(bound) tightly to the atom, they CANNOT be
easily moved to another atom nor make room
for more electrons.
• Insulator material includes glass, rubber, and
plastic
Materials Types
2. CONDUCTORS
•A CONDUCTOR is any material that easily
allows electrons (electricity) to flow.
•A CONDUCTOR has 1 to 3 free electrons in
the outer ring. Because atoms with 1 to 3
electrons in the outer ring are held (bound)
loosely to the atom, they can easily move to
another atom or make room for more electrons.
•Conductor material includes copper and gold
Materials Types
3. SEMICONDUCTORS
•Any material with exactly 4 free electrons in
the
outer
orbit
are
called
SEMICONDUCTORS.
•A semiconductor is neither a conductor or
insulator.
• Semiconductor material includes carbon,
silicon, and germanium.
•These materials are be used in the
manufacturer of diodes, transistors, and
integrated circuit chips.
Extrinsic Materials: n-Type and p-Type
The characteristic of semiconductor can be altered by
adding impurity through doping process (extrinsic
material)
Two type:
1) N-type
2) P-type
Extrinsic Materials : n-Type
•
•
•
•
N-type is created by
introducing impurity elements
that have five valence
electrons (pentavalent)
ex: antimony, arsenic,
phosphorus.
Note that four covalent bonds
are still present, however there
is additional fifth electron due
to impurity atom.
The remaining electron is free
to move within the newly
formed n-type material.
Diffused impurities with five
valence electrons are called
donor atoms.
Antimony impurity
in n-type material
Extrinsic Materials : p-Type
•
•
•
•
P-type is created by doping
with impurity atoms having
three valence electrons –
(boron- gallium, indium)
Note that there are
insufficient number of
electrons to complete
covalent bonds resulting a
hole
This hole is ready to accept
a free electron
The diffused impurities with
three valence electrons are
called acceptor atoms.
Boron impurity in
p-type material
Majority and Minority Carriers
•
•
In an n-type material - electron is called majority
carrier and hole the minority carrier
In a p-type material – hole is majority carrier and
electron is the minority carrier
•
•
•
•
Semiconductor Diode
Diode is formed by bringing these two material together p- and n-type.
Holes diffuse from the p side to the n side, leaving behind negatively
charged immobile negative ions.
Electrons diffuse from the n side to the p side, leaving behind positively
charged immobile positive ions.
Electrons and holes at joined region will combine, resulting in a lack of
carriers in the region near the junction (depletion region)
Reverse-Bias Condition (VD < 0V)
Reverse-biased p-n junction
Reverse-Bias Condition (VD < 0V)
•
•
•
•
The number of positive ions in the depletion region of n-type
will increase due to large number of free electrons drawn to
the positive potential.
The number of negative ions will increase in p-type resulting
widening of depletion region.
This region established great barrier for the majority carriers
to overcome, resulting Imajority = 0
A very small amount of reverse current does flow, due to
minority carriers diffusing from the (p/n) regions into the
depletion region and drifting across the junction.
Forward-Bias Condition (VD > 0V)
Forward-biased p-n junction
Forward-Bias Condition (VD = 0V)
• A semiconductor diode is forward-biased when the
association p-type and positive voltage and n-type
and negative voltage has been established.
• The application of forward-bias potential will pressure
the electrons in n-type and hole in p-type to
recombine with ions near the boundary and reduce
the width of depletion region
• The reduction in width of depletion region has
resulted in a heavy majority flow across the junction
•Lecture 2
Semiconductor Diodes
Figure 3.39 Simplified physical structure of the junction diode. (Actual geometries are given in Appendix A.)
Circuit
symbol
Diodes
Several types of diodes. The scale is centimeters
The i–v characteristic of a silicon diode.
Figure 3.7 The i–v characteristic of a silicon junction diode.
Figure 3.8 The diode i–v relationship with some scales
expanded and others compressed in order to reveal details.
The i–v characteristic of a silicon diode.
•
•
The Forward-Bias region:In the forward region the i- v relationship is closely approximated by…..
kv
Tk
i  I s (e
•
 1)
Is …….the reverse saturation current ( scale current)
– K = Boltzmann`s constant = 1.38*10-23 joules / kelvin
– Tk= the absolute temperature in kelvins = 273 + temperature in °C
The i–v characteristic of a silicon diode.
•
The Reverse-Bias region:-
•
The exponential term becomes negligibly small compared to unity, and the diode current
becomes…..
i  Is
•
That is, the current in the reverse direction is constant and equal to Is which tends to
zero.
•
The Breakdown Region:-
•
The breakdown region is entered when the magnitude of the reverse voltage exceeds a
threshold value that is specific to the particular diode, called the breakdown voltage.
Modeling the diode forward characteristic
The Piecewise-linear Model
Figure 3.13 Piecewise-linear model of the diode forward characteristic and its
equivalent circuit representation.
Figure 3.12 Approximating the diode forward
characteristic with two straight lines: the piecewiselinear model.
Figure 3.14 The circuit of
Fig. 3.10 with the diode
replaced with its piecewiselinear model of Fig. 3.13.
Modeling the diode forward characteristic
The Piecewise-linear Model
Example:
Given: VDD = 5V, VDO= 0.65, rD = 20 ,R= 1K
Thus
ID 
5  0.65
 4.26mA
1  0.02
VD = VDO+IDrD
Modeling the diode forward characteristic
The Constant-voltage-drop Model
Figure 3.15 Development of the constantvoltage-drop model of the diode forward
characteristics. A vertical straight line (B) is used
to approximate the fast-rising exponential.
Observe that this simple model predicts VD to
within 0.1 V over the current range of 0.1 mA to
10 mA.
Figure 3.16 The constant-voltage-drop model of the diode forward
characteristics and its equivalent-circuit representation.
Modeling the diode forward characteristic
The Ideal Diode Model
Figure 3.1 The ideal diode: (a) diode circuit symbol; (b) i–v characteristic; (c) equivalent circuit in the
reverse direction; (d) equivalent circuit in the forward direction.
Operation in The reverse Breakdown
Region- Zener Diodes
Figure 3.20 Circuit symbol for a zener diode.
Figure 3.22 Model for the zener diode.
Figure 3.21 The diode i–v characteristic with the breakdown region shown in some detail.
Operation in The reverse Breakdown
Region- Zener Diodes
Example: Find I ?
Figure 3.23 (a) Circuit for Example 3.8. (b) The circuit with the zener diode replaced with its equivalent circuit model.
Special Diode Types
Light-Emitting Diodes (LEDs)
Series Diode Configurations with DC Inputs
• For the series diode configurations that will be considered, the
first thing to do is to determine the state of the diode “ ON” or
“OFF”
• In the “ON” state, the diode may be replaced with a constant
voltage drop ( 0.7V) or a short circuit based on the model of
approximation.
• In the OFF state, diode is replaced with an open circuit.
• Example 2.8, and Example 2.9
Parallel and Series Parallel Configurations
• The method applied before can be extended to the
analysis of parallel and series-parallel configurations
where more than one diode is contained in the circuit,
simply match the sequential series steps applied to
series diode configurations
– Example 2.12 and Example 2.15
Diode Applications
Lecture 3
AND/OR Gates

AND and OR gates represent basic components of computers that
are used to implement Boolean algebra.
OR-Gate
AND-Gate
1
2
3
1
2
3
0
0
0
0
0
0
0
1
1
0
1
0
1
0
1
1
0
0
1
1
1
1
1
1
If logic “1” is represented by +10 (+5) V and logic “0” is
represented by 0 V, the OR and the AND gates can be
represented by the following diode combinations;
AND/OR Gates


For the OR gate;
– D1ON
– D2 OFF
– V0=10V ( logic 1)
For the AND gate;
– D1 OFF
– D2 ON
– V0=0V ( logic 0)
Diodes Applications: Rectifier Circuits
Figure 3.24 Block diagram of a dc power supply.
The rectifier with a filter capacitor
The rectifier with a filter capacitor
HWR Circuit With
Smoothing Capacitor