Email: hisham.elsherif@guc.edu.eg
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
1
Schedule of Classes
• Lectures:
- Sunday 13:45 pm to 15:30 in B2-312.
Instructor office hours every Tuesday
from 12:30 pm to 1:30 p.m. in C3 room 215
• Tutorials :
- Included in Lectures
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
2
Tutorials
• Every week the instructor will assign a problem set from the text
book that deals with the covered sections in the lectures.
• In the tutorial, some of the assigned problems will be worked out on
the board.
• At the end of some tutorials you will be asked to solve and submit
one or two of the assigned problems. (At least three quizzes will be
conducted during this course).
• At the beginning of the following week you will be asked to hand in
another set of problems (assignment).
• The full solutions of each problem set will be posted at the end of
the week.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
3
Marking Scheme
Lab Activity
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
5%
ELCT708: Electronics for Biotechnology
4
Course Objectives
Upon successful completion of this course, you should be able to:
•
Identify the main components of electric circuits.
•
Write the equations that govern the operation of Direct Current (D.C.)
electric circuits.
•
Apply frequency domain analysis technique to solve Alternating
Current (A.C.) circuits.
•
Examine the circuit response under different frequencies.
•
Determine the main characteristics of electronic analog and digital
circuits.
•
Analyze the performance of practical electrical systems.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
5
Course Contents
I- Circuit concepts.
II- Circuit Analysis Techniques.
III- Time Dependent Circuit analysis.
IV- Analog Building Blocks and Operational Amplifiers.
V- Semiconductor Devices.
VI. Practical Applications.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
6
Text Book
• Recommended Textbook
Alexander & Sadiku, Fundamental of Electric Circuits.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
7
Useful Advices
– Please try to attend all lectures, and tutorials for your own
benefits and be on time.
– Please hand in the assignments and quizzes on time, late
assignments will be rejected.
– Update your instructor with any problem that might arise in
the tutorial.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
8
•
Why study electric circuits?
– Building block of any electrical system.
•
What are electric circuits?
– A model of real life electrical system.
– Interconnections between electric elements.
•
What are the main circuit components?
– Energy Sources. (batteries)
– Energy storing or consuming elements. (resistors)
•
What are the main circuit variables?
– Voltage, current and Power.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
9
Chapter 1
Circuit Elements
•
Objectives.
• Introduction.
• Current.
• Voltage.
• Power and Energy
• Circuits Elements
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
10
Objectives
•
To introduce the active and passive circuit elements.
•
To be able to identify the ideal voltage and current sources.
•
To define the characteristics of the different types of dependent
sources.
•
To write the mathematical expression for the voltage- current
relationship of resistors (Ohm’s Law).
•
To be able to write KVL for every loop in the circuit. And to solve the
KVL equations, especially for simple circuits.
•
To be able to write KCL at every node in the circuit and to solve the
KCL equations, especially for simple circuits.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
11
Introduction
An electric circuit is an interconnection of electrical elements.
Simple Electric Circuit
complicated real circuit
this circuit can be
analyzed using the
techniques we shall
cover
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
12
DC Circuits
Charge and Current
Charge is an electrical property of the atomic particles of which matter
consists, measured in coulombs (C).
• The flow of electric charges. Is a unique feature of electric charge.
• Electricity is the fact that it is mobile; that is, it can be transferred from one
place to another.
• It can be converted to another form of energy.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
13
As each electron moves uniformly through a conductor, it
pushes on the one ahead of it, such that all the electrons
move together as a group.
The tube is full of marbles, just as a conductor is full of
free electrons ready to be moved by an outside influence.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
14
current flow
• When a conducting wire (consisting of several atoms) is connected
to a battery (a source of electromotive force).
• The charges are compelled to move; positive charges move in one direction
while negative charges move in the opposite direction.
•This motion of charges creates electric current.
• It is conventional to take the current flow direction as the movement of
positive charges,
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
15
Current (I)
• Current: measures flow of charge in time. Symbol: “i”; Unit: Ampere (A)
dq
i=
dt
Mathematically, the
relationship between current
i, charge q, and time t
!
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
16
The charge transferred between time t0 and t is obtained by integrating
both sides.
If the current does not change with time,
but remains constant, we
call it a direct current (dc).
A direct current (dc) is a current that remains constant with time.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
17
A time-varying current is represented by
the symbol i. A common
form of time-varying current is the
sinusoidal current or alternating
current (ac).
An alternating current (ac) is a current that varies sinusoidally with time.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
18
Voltage (V)
Voltage (or potential difference) is the energy required to move a unit charge
through an element, measured in volts (V).
• Voltage: Potential to do “Work”
– Symbol: “V”
– Unit: Volts (V)
•
1 Volt is 1 Joule/1 Coulomb
mathematically,
dw
v=
dq
where
w is energy in joules (J)
q is charge in coulombs (C).
– i.e. potential energy per unit charge
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
19
(1)
(2)
• The figure shows the voltage across an element. connected to points a and b.
• The plus (+) and minus (−) signs are used to define reference direction or
voltage polarity.
• The vab can be interpreted in two ways:
• (1) point a is at a potential of vab volts higher than point b, or
• (2) the potential at point a with respect to point b is vab.
vab = −vba
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
20
Power and Energy
Power is the time rate of expending or absorbing energy, measured in watts (W).
– Symbol: p
– Units: Watts (W)
dw
dw
p=
=
dt
dq
P=vi
V
dq
dt
Where
p is power in watts (W),
w is energy in joules (J),
t is time in seconds (s)
i
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
21
Default Sign Convention
• Passive sign convention : current should enter
the positive voltage terminal.
I
+
Circuit Element
–
P=VI
– Positive (+) Power: element absorbs power
– Negative (-) Power: element supplies power
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
22
The power P = v i is a time-varying quantity and is called the instantaneous power
Thus,
•the power absorbed or supplied by an element is the product of the voltage and
the current .
•If the power has a + sign, power is being delivered to or absorbed by the element.
•If, the power has a − sign, power is being supplied by the element.
How to know that P is +ve or -ve sign
By the passive sign convention
when the current enters through the positive terminal of an element p = +vi.
When the current enters through the negative terminal, p = −vi.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
23
Example
Find the power delivered or absorbed by each element
Absorbing
Element
Absorbing
element
p=4 3
= 12 W,
Absorbing
element
p=4 3
= 12 W,
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
Supplying
element
p = 4 (−3)
= −12 W,
Supplying
element
p = 4 (−3)
= −12 W,
ELCT708: Electronics for Biotechnology
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Example
•
Calculate the power delivered or absorbed by each element in the
shown circuit. Show that the sum of the delivered power = sum of the
absorbed power.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
25
Solution
P5
P2
P6
P3
P1
P4
P1 " # $$ $ " # $$$%
&( " )$ ' " *$$%
&) " # $ ' " #'$%
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
&' " '$ $ " '$$%
+ " ($ ' " (*$%
&* " #,$ ' " # +$%
ELCT708: Electronics for Biotechnology
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P2
P6
P3
P1
P4
P (supplied) = (-1000) + (-20) + (-140) = -1160 W
P (absorbed) = 200 + 600 + 360 = 1160 W
P (supplied) + P (absorbed) = 0
Power absorbed = −Power supplied
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
27
Circuit Elements
Types of elements found in electric circuits:
• Active elements; are capable to generating energy (sources)..
Example
generators, batteries, and operational amplifiers.
• Passive elements; don'
t generate energy, they are energy consuming
(storing) elements
.
Example
resistors, capacitors, and inductors..
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
28
Active Elements
R
C
L
The most important active elements are voltage or current sources
that generally deliver power to the circuit connected to them. There are
two kinds of sources:
• Independent sources
• Dependent sources.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
29
An ideal independent source is an active element that provides
a specified voltage or current that is completely independent of
other circuit variables.
used for constant or
time-varying voltage
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
used for
constant voltage (dc).
ELCT708: Electronics for Biotechnology
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Ideal Voltage Source
The ideal voltage source explicitly defines
Vs
the voltage between its terminals.
– Constant (DC) voltage source:
+
−
Vs = 5 V
– Time-Varying voltage source: Vs = 10 sin(t) V
– Examples: batteries, wall outlet, function generator.
The ideal voltage source does not provide any information about the current
flowing through it.
The current through the voltage source is defined by the rest of the circuit to
which the source is attached. Current cannot be determined by the value of
the voltage.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
31
Ideal Current Source
An ideal independent current source is an active element that provides a
specified current completely independent of the voltage across the source.
That is,
the current source delivers to the circuit whatever voltage is necessary to
maintain the designated current.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
32
•
•
•
•
The ideal current source sets the
Is
value of the current running through it.
– Constant (DC) current source: Is = 2 A
– Time-Varying current source: Is = -3 sin(t) A
– Examples: few in real life!
The ideal current source has known current, but unknown voltage.
The voltage across the voltage source is defined by the rest of the circuit to
which the source is attached.
Voltage cannot be determined by the value of the current.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
33
I-V Relationships Graphically
i
i
v
v
Ideal Voltage
Source: Vertical
line
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
Ideal Current
Source:
Horizontal line
ELCT708: Electronics for Biotechnology
34
Source Combinations
v1
v2
v1 + v2
–
+
–
+
•
Voltage sources in series can be replaced by an equivalent voltage source:
–
+
•
Current sources in parallel can be replaced by an equivalent current source:
i1
i2
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
i1+ i2
ELCT708: Electronics for Biotechnology
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Dependent Source
An ideal dependent (or controlled) source is an active element in which the
source quantity is controlled by another voltage or current.
dependent
voltage source
dependent
current source.
Dependent sources are usually designated by diamond-shaped symbols,
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
36
Example: You watch a certain voltmeter V1 and manually adjust
a voltage source Vs to be 2 times this value. This constitutes a
voltage-dependent voltage source.
Circuit A
+
V1
-
2V1
+
-
Circuit B
This is just a manual example, but we can create such dependent
source electronically.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
37
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
38
We can have voltage or current sources depending on voltages or currents
elsewhere in the circuit.
Here, the voltage V provided by the dependent source (right) is proportional
to the voltage drop over Element X. The dependent source does not need
to be attached to the Element X in any way.
+
Element x
VX
+
-
V = A V VX
A diamond-shaped symbol is used for dependent sources, just as a
reminder that it’s a dependent source.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
39
There are four possible types of dependent sources
1. A voltage-controlled voltage source (VCVS).
2. A current-controlled voltage source (CCVS).
3. A voltage-controlled current source (VCCS).
4. A current-controlled current source (CCCS).
Example of a current controlled voltage source
the voltage 10i of the voltage source depends on the current I through element C
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
40
The 4 Basic Dependent Sources
Voltage-controlled voltage source … V = Av Vcd
Current-controlled voltage source … V = Rm Ic
Current-controlled current source … I = Ai Ic
Voltage-controlled current source … I = Gm Vcd
+
_
Av Vcd
+
_
Rm Ic
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
Ai Ic
Gm Vcd
ELCT708: Electronics for Biotechnology
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For the following circuits:
Calculate the source output voltage or current.
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
42
Example
Calculate the power supplied or absorbed by each element
P1 = -(20)(5) = -100W
P2 = (12)(5) = 60W
P3 = (8)(6) = 48W
P4 = -(8)(0.2)(5) = 8W
P1 + P2 + P3 + P4 = −100 + 60 + 48 − 8 = 0
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
43
Example
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
44
P1 = -(10)(3) = -30W
P2 = -(6)(2) = -12W
P3 = (6)(I0) = 6I0W
P4 = -(12)(9) =-108W
P5 = -(4)(8) =-32W
P6 = (8)(2)(11) = 176W
6I0 -32 -12 -108 +176 = -182 + 6I0 +176 = 0
Hisham
El-Sherif
I oDr.-Eng.
=
1
[
A
]
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
45
Example
Compute the power absorbed or supplied by each component of the circuit
P1 = -(5)(8) = -40W
P2 = (2)(8) = 16W
P3 = (0.6)(5)(3) = 9W
P4 = (3)(5) = 15W
Absorbed Power = 16 + 9 + 15 = 40W
Supplied Power = - 40W
Dr.-Eng. Hisham El-Sherif
Electronics and Electrical Engineering Department
ELCT708: Electronics for Biotechnology
46