# Chapter 1 - Introduction of Semiconductor ```ECT – Electronics 1
Prepared by Ms Nur Aishah Bt Azriy
B. Eng (Hons) in Mechatronics Engineering (Automotive)
Learning Outcome
• This course covers fundamentals of analogue electronics which comprises
of topics such as: the concept of semiconductors and electronic devices and
its application, together with hands on practical.
• The course learning outcome divided in three cores:
CLO 1
Describe the concepts of semiconductor and
characteristics curve the various types of diodes and
transistors
CLO 2
Explain the operation of semiconductor devices and
circuit operation the various types of diodes and
transistors.
CLO 3
Evaluate the current, voltage and power in circuits of
diodes and transistors
Assessment Methods
Distribution
Percentage
CLO 1
CLO 2
CLO 3
Class Test 1
10 %
&times;
Class Test 2
10 %
&times;
&times;
&times;
Assignment
10 %
&times;
&times;
Tutorials
30 %
&times;
&times;
&times;
Final Exam
40 %
&times;
&times;
&times;
Total
100 %
&times;
&times;
&times;
List of Courses
Title
Sub Title
Introduction
Basic definitions, types of elements, Ohm's Law, types of components
AC Circuit
Theory of
Semiconductors
Theory of Diode
Diode Circuits :
Basic definitions of AC circuit, Introductions of Oscilloscope, Capacitors,
Inductors,
Conductors, semiconductors, silicon crystals, intrinsic semiconductors,
doping a semiconductor, two types of extrinsic semiconductors, The
Operation of diodes. Unbiased diode, forward bias, reverse bias,
breakdown, energy levels, reverse biased diode
Basic ideas, ideal diode, diode approximations, diode I-V characteristic
Basic diode circuit. Half-wave rectifier, full-wave rectifier, bridge rectifier,
capacitor-input filter. To acquire hands-on laboratory experience, utilizing
oscilloscopes and other modern test equipment. Peak inverse voltage,
clippers and limiters, clampers. To acquire hands-on laboratory
experience, utilizing oscilloscopes and other modern test equipment.
Assessment Schedule
WEEK NO.
Class Test 1
Class Test 2
Assignment
Tutorials
Final Exam
1
2
3
4
5
6
7
8
9
Chapter 1 - Introduction
Learning the basic of electronics element
INTRODUCTION
• Knowing about quantities and electric unit is
important to understand the process of circuit’s
operation.
• Quantities is something that can be measured
and unit is based on name of that certain
quantities.
• In this electrical and electronics subjects, it is
important to understand the basic quantities SI
unit for charge (Q), current (I), voltage (V),
resistor (R), power (P), and energy (W).
System of Units
• As engineers, we deal with measurable quantities.
• Such an international measurement language is the International
System of Units (SI).
• In this system, there are six principal units from which the units of
all other physical quantities can be derived.
Quantity
Length
Mass
Time
Electric Current
Temperature
Luminous intensity
Basic Unit
Meter
kilogram
second
ampere
Kelvin
candela
Symbol
M
kg
s
A
K
Cd
System of Units
 Knowing your units is important!
 Kilo and Mega are common inresistors
 Milli, micro, nano and pico can be used in other components
Multiplier
1012
109
106
103
10-3
10-6
10-9
10-12
Prefix
Tera
giga
mega
kilo
milli
micro
nano
pico
Symbol
T
G
M
K
m
&micro;
n
p
BASIC CONCEPTS AND DEFINITIONS
1.
CHARGE
• The most basic quantity in an electric circuit is the electric
charge.
• We all experience the effect of electric charge when we try to
remove our wool sweater and have it stick to our body or walk
across a carpet and receive a shock.
• Charge is an electrical property of the atomic particles of
which matter consists, measured in coulombs (C).
• Charge, positive or negative, is denoted by the letter q or Q.
BASIC CONCEPTS AND DEFINITIONS
1.
CHARGE
• We know from elementary physics that all matter is made of
fundamental building blocks known as atoms and that each
atom consists of electrons, protons, and neutrons.
• We also know that the charge ‘e’ on an electron is negative
and equal in magnitude to 1.602x10−19 C, while a proton
carries a positive charge of the same magnitude as the
electron and the neutron has no charge.
• The presence of equal numbers of protons and electrons
leaves an atom neutrally charged.
BASIC CONCEPTS AND DEFINITIONS
2.
CURRENT
• Current can be defined as the motion of charge through a
conducting material, measured in Ampere (A).
• Electric current, is denoted by the letter i or I.
• Mathematically,
𝐶ℎ𝑎𝑟𝑔𝑒 𝑄
𝐼=
=
𝑇𝑖𝑚𝑒
𝑡
BASIC CONCEPTS AND DEFINITIONS
2.
CURRENT
• Two types of currents:
1) A direct current (DC) is a current that remains constant with
time.
2) An alternating current (AC) is a current that varies with
time.
Fig 1. 2 Two common types of current: (a) direct current (DC), (b) alternative current (AC)
EXAMPLE 1
• Determine the current in a circuit if a charge of 80 coulombs
passes a given point in 20 seconds (s).
Solution:
𝑄 80
𝐼= =
=4𝐴
𝑡 20
EXAMPLE 2
How much charge is represented by 4,600 electrons?
Solution:
Each electron has - 1.602x10-19 C. Hence 4,600 electrons will have:
-1.602x10-19x4600 = -7.369x10-16 C
BASIC CONCEPTS AND DEFINITIONS
3.
VOLTAGE
• By definition:
One volt is the potential difference (voltage) between two points when
one joule of energy is used to move one coulomb of charge from one
point to the other.
• The unit of voltage is the volt (V).
BASIC CONCEPTS AND DEFINITIONS
3.
VOLTAGE
• A battery is a type of voltage source that converts chemical
energy into electrical energy.
• Solar Cells convert light energy into electrical energy.
• Generators convert mechanical energy into electrical energy.
• Electronic power supplies (voltage converters)?
• They do not produce electrical energy, but they transform the ac
voltage from the wall outlet into a constant de voltage for use in our
circuits.
BASIC CONCEPTS AND DEFINITIONS
4.
RESISTANCE
• The property of a material that
restricts the flow of electrons is
called resistance.
• The unit of Resistance is Ohm (Ω).
• By definition:
One ohm of resistance exists if there is
one ampere of current in a material
when one volt is applied across the
material.
BASIC CONCEPTS AND DEFINITIONS
4.
ENERGY AND POWER
• Energy is the ability to do work - joules (J)
• Power is the rate at which energy is used - in watts (W)
• By definition:
One watt is the amount of power when one joule of energy used in
one second.
𝑄 𝐸𝑛𝑒𝑟𝑔𝑦, 𝑊 𝐸𝑛𝑒𝑟𝑔𝑦, 𝑊
𝑃𝑜𝑤𝑒𝑟 = 𝐼𝑉 = =
=
𝑡
𝐶ℎ𝑎𝑟𝑔𝑒, 𝑄
𝑇𝑖𝑚𝑒, 𝑡
EXAMPLE 3
An electric heater consumes 1.8Mj when connected to a 250 V supply for 30
minutes. Find the power rating of the heater and the current taken from the
supply.
Solution:
P = W/t = (1.8&times;10^6)/ (30&times;60) = 1000 W
Power rating of heater = 1kW
P=VI
Thus
I=P/V=1000/250=4A
Hence the current taken from the supply is 4A.
Ohm’s Law
• Ohm’s law describes mathematically how
voltage, current, and resistance are related.
• Hence, current and voltage are linearly
proportional.
• In resistive circuits, with a constant resistance, if
voltage increases or decreases by a certain
percentage, so will current.
• On the other hand, current and resistance are
inversely related.
• With constant voltage, if resistance is reduced,
current goes up; when resistance is increased,
current goes down
Resistors
 A resistor impedes the flow of electricity through a circuit.
 Resistors have a setvalue.
 Since voltage, current and resistance are related through Ohm’s
law, resistors are a good way to control voltage and current in
More on resistors
 Resistor colorcodes
1st band =
2nd band =
3rd band =
4th band =
1st number
2nd number
# of zeros / multiplier
tolerance
Color code
 Tolerance: Gold = within 5%
Capacitors
 A capacitor stores electricalenergy.
 This pool of electrons is available for electronic components to
use.
Capacitance is measured in Farads. The small capacitors usually used in
Some capacitors are polarized. Notethe
different length terminals on one of the capacitors.
Polarity of capacitors
 The shorter terminalgoes
on the negativeside.
 The stripe is on the
negative terminal sideof
the capacitor.
 The board is marked for
positive or negative.
Applications of capacitors
 Capacitors supply a pool of electrons for immediate use.

If a component needs an immediate supply of electrons, the
capacitor can supply thoseelectrons.
 Capacitors can smooth out a signal – eliminate the ripples
or spikes in DCvoltage.

The capacitor can absorb the peaks and fill in the
valleys of a rippledsignal.
Diode
 A diode is a one way valve (or gate) for electricity. It is a
component with an asymmetrical transfer characteristic. A
diode has low (ideally zero) resistance in one direction, and
high (ideally infinite) resistance in the other direction.
 Diodes will protect yourelectronics.
Diode circuit protection
 In a DPDT switch, if polarity is wrong, the motor will run
backwards.
 In an electronic circuit, if the polarity is wrong, you can fry
A diode in your system will help to prevent problems.
Diodes have a bar
on the cathode
(negative) side.
Light emitting diode (LED)
 A light emitting diode (LED) is a semiconductor light source.
When electricity is passing through the diode, it emits light.
 Jeremy is going to talk a lot more about LEDs.
Variable resistor / Potentiometer
 A potentiometer is a variable resistor. As you manually
turn a dial, the resistance changes.
How a variable resistor works
 As the dial/wiper turns, electricity must go through
more or less of the resistive strip.
In series, the change in resistance means a change in voltage.
 So as you turn the
dial/wiper, you get
a change involtage.
Transistors
 A transistor is a semiconductor device used to amplify
and switch electronic signals and electrical power.
 This is our electronicswitch!
How a transistor works
 A voltage or current applied to one pair of the
transistor’s terminals changes the current through
another pair of terminals.
 A transistor is composed of semiconductor material
with at least threeterminals
for connection to an external
circuit.
Transistors have 3 pins.
For these transistors:
Collector
Emitter
Base
Terminology
 BJT versus FET
 Bipolar junction transistor. Useful asamplifiers.
Collector, Emitter, Base
 Field-effect transistor. Useful as motordrivers.
Source, Drain, Gate
MOSFET: Metal-oxide-semiconductorFET
 NPN (N-channel FET) versus PNP (P-channel FET)
 NPN versus PNP is how the semiconductors are
layered. NPN: Not pointing in
PNP: Pointing in permanently
Schematic symbols
BJT PNP
P-channel FET
BJT NPN
N-channel FET
Integrated circuit
 An integrated circuit (IC) is a set of transistors that is
the controller or ‘brain’ of an electronic circuit.
 An input is received, an output is sent out.
Modern microprocessor ICs can have billions of
transistors per squareinch!
What an IC can do for us?
 Billions of electronically controlled on/offswitches
(transistors) is how the microprocessor in a digital
computer ‘thinks’ and functions.

A computer has a wide range of tasks to perform.
But other ICs can complete simpler, discrete jobs.
For example, an IC can take a voltage input and output
commands to a motor.
IC Terminology: Op-amp
 An operational amplifier (op-amp) is a set of
transistors inside the integrated circuit. They often are
the components doing the mathematicaloperations.
Printed Circuit Board
 Components are attached to a printed
circuit board.
 The ‘front’ side of the board will have
printed component information, such
as resistor # and resistance, diode type
and polarity, etc.
 Holes go all the way through the board
from one side to the other. Throughhole soldering is needed to connect
components to the board.
Back of Circuit Board
 The ‘back’ sideof the board will have lines indicating
connections between components. The lines on the
back are similar towires.
 Thicker lines denote more current (electrons)moving
through.
 Components connect the lines.
End of Chapter 1
Got any questions?
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