Download File - Vijay Solanki

Basic Electronics (Chapter_01)
Prepared By Vijay Solanki
Unit: 01. Introduction to Analog Electronics
Major Learning Outcomes
1) Introduction to analog electronics.
2) Explain various analog electronics terminology
Basic Electronics By Vijay Solanki
Topics & Subtopics
1.1 Active & Passive Components
1.2 Voltage and Current Sources.
1.3 Symbols of various semiconductors.
1.4 Important definitions.
i) Amplitude, Frequency, Phase, Wavelength
ii) Signal, Waveform, Spectrum, Time and
frequency domain representation.
1.5 Signal and their responses.
i)Unit step, Unit impulse and Unit Ramp.
ii)Parabolic, Triangular and saw tooth
Page 1
Basic Electronics (Chapter_01)
Prepared By Vijay Solanki
Introduction to analog electronics
1.1 Active & Passive Components
All electrical components can be divided into two main categories as active and passive devices. The
categorization is based on components’ capability to produce energy to the circuit. If any component
delivers the power to the circuit, it belongs to the active components category. If the component utilizes
energy, it is called a passive element.
Active Components
Passive Components
Any component that is capable of providing a
power gain is called an active component.
They inject power to the circuit, and can control
the current (or energy) flow within the circuit.
Components that cannot provide any power gain
to the circuit are called passive devices.
These devices are incapable of controlling the
current (energy) flow in the circuit and need the
help of active devices to operate.
Any electronic circuit should contain at least one
active component to operate.
Some examples for active devices are battery,
vacuum tubes, transistor and SCR (silicon
controlled rectifier / thyristor).
Controlling the current flow in circuit may be
helped by another small current or voltage. They
are called current controlled devices (ex: Bipolar
Junction Transistor) and voltage controlled
devices (ex : Field Effect Transistor).
Electronic circuit not required any passive
component to operate.
Some examples for passive devices are resistors,
inductors and capacitors.
Active devices inject power to the circuit
passive devices are incapable of supplying any
energy
Passive devices are incapable of providing power
gain.
Active devices are capable of providing power
gain
Active devices can control the current (energy)
flow within the circuit
Basic Electronics By Vijay Solanki
Although passive components cannot amplify a
signal with a gain more than one, they can multiply
a signal by a value less than one. They also can
oscillate, phase shift and filter signals. Some
passive components also have the capability to
store energy (drawn from an active element) and
release later. Example: capacitors and inductors.
Passive devices cannot control it.
Page 2
Basic Electronics (Chapter_01)
Prepared By Vijay Solanki
1.2 Voltage and Current Sources.
Two types of Voltage and Current Sources Available:
1. Ideal and Practical Sources.
2. Controlled Sources.
1. Ideal and Practical Sources
A mathematical model of an electric circuit contains ideal models of physical circuit
elements. Some of these ideal circuit elements (e.g. , the resistor, capacitor, inductor, and
transformer).
1) Ideal Sources:
The ideal independent voltage source constrains the terminal voltage across the element
to a prescribed function of time, vS(t), as v(t) = vS(t).
The polarity of the source is denoted by ± signs within the circle which denotes this as an
ideal independent source.
The current through the element will be determined by the circuit that is attached to the
terminals of this source.
The ideal independent current source constrains the terminal current through the
element to a prescribed function of time, iS(t), as i(t) = iS(t).
The polarity of the source is denoted by an arrow within the circle which also denotes
this as an ideal independent source.
Basic Electronics By Vijay Solanki
Page 3
Basic Electronics (Chapter_01)
Prepared By Vijay Solanki
The voltage across the element will be determined by the circuit that is attached to the
terminals of this source.
2) Practical Sources:
The preceding ideal independent sources constrain the terminal voltage or current to a
known function of time independent of the circuit that may be placed across its terminals.
Practical sources, such as batteries, have their terminal voltage (current) dependent upon
the terminal current (voltage) caused by the circuit attached to the source terminals. A
simple example of this is an automobile storage battery.
The battery’s terminal voltage is approximately 12 V when no load is connected across
its terminals.
When the battery is applied across the terminals of the starter by activating the ignition
switch, a large current is drawn from its terminals.
2. Controlled Sources
A voltage or current source whose intensity is controlled by a circuit Voltage or current
elsewhere in the circuit.
When the analysis of electronic (nonreciprocal) circuits became important in circuit theory,
controlled sources were added to the family of circuit elements.
What Are Controlled Sources?
By source we mean a voltage or current source in the usual sense. By controlled we mean that the
strength of such a source is controlled by some circuit variable(s) elsewhere in the circuit.
Basic Electronics By Vijay Solanki
Page 4
Basic Electronics (Chapter_01)
Prepared By Vijay Solanki
Four Types of controlled Sources are there.
1.
2.
3.
4.
Current-controlled voltage source (CCVS)
Voltage-controlled Current source (VCCS)
Current-controlled Current source (CCCS)
Voltage -controlled voltage source (VCVS)
1.3 Symbols of various semiconductors
Basic Electronics By Vijay Solanki
Page 5
Basic Electronics (Chapter_01)
Basic Electronics By Vijay Solanki
Prepared By Vijay Solanki
Page 6
Basic Electronics (Chapter_01)
Basic Electronics By Vijay Solanki
Prepared By Vijay Solanki
Page 7
Basic Electronics (Chapter_01)
Basic Electronics By Vijay Solanki
Prepared By Vijay Solanki
Page 8
Basic Electronics (Chapter_01)
Basic Electronics By Vijay Solanki
Prepared By Vijay Solanki
Page 9
Basic Electronics (Chapter_01)
Basic Electronics By Vijay Solanki
Prepared By Vijay Solanki
Page 10
Basic Electronics (Chapter_01)
Prepared By Vijay Solanki
Explain various analog electronics terminology
1.4 Important definitions
i) Amplitude:
Amplitude is a measure of how big the wave is.
Imagine a wave in the ocean. It could be a little ripple or a giant tsunami.
What you are actually seeing are waves with different amplitudes.
They might have the exact same frequency and wavelength, but the amplitudes of the
waves can be very different.
The amplitude of a wave is measured as:
1. the height from the equilibrium point to the highest point of a crest or
2. the depth from the equilibrium point to the lowest point of a trough
When you measure the amplitude of a wave, you are really looking at the energy of the wave.

It takes more energy to make a bigger amplitude wave.

Anytime you need to remember this, just think of a home stereo’s amplifier…
it makes the amplitude of the waves bigger by using more electrical energy.
Basic Electronics By Vijay Solanki
Page 11
Basic Electronics (Chapter_01)
Prepared By Vijay Solanki
ii) Frequency:
When we first started looking at SHM we defined period as the amount of time it takes
for one cycle to complete... seconds per cycle.
 Frequency is the same sort of idea, except we’re just going to flip things around.
 Frequency is a measurement of how many cycles can happen in a certain amount of time…
cycles per second.
 If a motor is running so that it completes 50 revolutions in one second, I would say that it
has a frequency of 50 Hertz.
 Hertz is the unit of frequency, and just means how many cycles per second.
o
It is abbreviated as Hz.
o
It is named after Heinrich Hertz, one member of the Hertz family that made many
important contributions to physics.
 In formulas frequency appears as an "f".
Since frequency and period are exact inverses of each other, there is a very basic pair of
formulas you can use to calculate one if you know the other…
Example 1: The period of a pendulum is 4.5s. Determine the frequency of this pendulum.
The period means that it will take 4.5 seconds for the pendulum to swing back and forth once.
So, I expect that my frequency will be a decimal, since it will complete a fraction of a swing per
second.
Basic Electronics By Vijay Solanki
Page 12
Basic Electronics (Chapter_01)
Prepared By Vijay Solanki
iii) Phase:
The phase is the fraction of the cycle that you have reached at any given point.
If the point is not specified, it may be assumed to be 0º.
The start of the cycle is the point where the wave is 0 and going from negative to
positive. (If the wave is not a sine curve, there may be more than one such point in a
complete cycle so the starting point may be arbitrary.) For sin θ the phase at 0º is 0; for cos
θ it is ¼.
If the cycle has wavelength 360º or 2π radians, the phase is often expressed as an angle
corresponding to the given fraction of the wavelength, so the phase of cos θ at 0º is 90º or
½π radians.
It is assumed that the average value of the wave is 0. If the wave is say sin θ + 4, it is
never zero so to define the phase we would need the point where it reaches its average
value (4 in this case).
IV) Wavelength:
 The distance between adjacent peaks in a series of periodic waves.
Wavelength is a property of a wave that most people (once they know what to look for)
can spot quickly and easily, and use it as a way of telling waves apart. Look at the following
diagram...

Any of the parts of the wave that are pointing up like mountains are called
crests. Any part that is sloping down like a valley is a trough.
Basic Electronics By Vijay Solanki
Page 13
Basic Electronics (Chapter_01)

Prepared By Vijay Solanki
Wavelength is defined as the distance from a particular height on the wave
to the next spot on the wave where it is at the same height and going in the
same direction.
o

Usually it is measured in meters, just like any length.
There isn’t a special spot you have to start on a wave to
measure wavelength, just make sure you are back to the same height
going in the same direction. Most people do like to measure from
one crest to the next crest (or trough to trough), just because they are
easy to spot.
On a longitudinal wave, the wavelength is measured as the distance between the
middles of two compressions, or the middles of two expansions.
This leads us to one of the most important formulas you will use when studying waves.

Frequency tells us how many waves are passing a point per second, the
inverse of time.

Wavelength tells us the length of those waves in meters, almost like a
displacement.

If we multiply these two together, we are really multiplying 1/s and m…
which gives us m/s, the velocity of the wave!
Basic Electronics By Vijay Solanki
Page 14
Basic Electronics (Chapter_01)
Prepared By Vijay Solanki
v = velocity of the wave (m/s)
f = frequency (Hz)
λ = wavelength (m)
v) Signal:
A Signal is the data being transmitted from one device to another, this includes (but not
limited to) binary serial data, pulse width modulation (PWM), sound.
VI) Waveform:
The waveform is the shape of the transmitted signal, serial data and PWM would take on
a square wave waveform whereas sound from a speaker would appear (generally) as a sine
wave.
viii) Spectrum:
A spectrum consisting of bright lines at certain wavelengths separated by dark regions in
which there is no light.
ix) Time and Frequency domain Representation:
Electrical signals have both time and frequency domain representations.
In the time domain, voltage or current is expressed as a function of time as illustrated in
Figure.
Basic Electronics By Vijay Solanki
Page 15
Basic Electronics (Chapter_01)
Prepared By Vijay Solanki
Most people are relatively comfortable with time domain representations of signals.
Signals measured on an oscilloscope are displayed in the time domain and digital
information is often conveyed by a voltage as a function of time.
Signals can also be represented by a magnitude and phase as a function of frequency.
1.5 Signals and their responses
The important signals for circuits include the step, impulse, ramp, sinusoid, and dc
signals.
These signals are widely used and are described here in the time domain. All of these
signals have a Laplace transform.
i)Unit Step:
Function of time that is zero for t < t0 and unity for t > t0. At t = t0 the magnitude changes
from zero to one. The unit step is dimensionless.
The unit-step function u(t) is defined mathematically by,
Here unit step means that the amplitude of u(t) is equal to 1 for t ³ 0.
 Note that we are following the convention that u(0) = 1. From a strict mathematical
standpoint, u(t) is not defined at t = 0.
Nevertheless, we usually take u(0) = 1. If A is an arbitrary nonzero number, Au(t) is the
step function with amplitude A for t ³ 0.
The unit step function is plotted in Figure below.
Basic Electronics By Vijay Solanki
Page 16
Basic Electronics (Chapter_01)
Prepared By Vijay Solanki
ii)Unit Impulse:
A very short pulse such that its value is zero for t ¹ 0 and the integral of the pulse is 1.
The unit impulse d(t), also called the delta function or the Dirac distribution, is defined
by,
iii)Unit Ramp:
A continually growing signal such that its value is zero for t <= 0 and proportional to time
t for t > 0.
The unit-ramp function r(t) is defined mathematically by,
Basic Electronics By Vijay Solanki
Page 17
Basic Electronics (Chapter_01)
Prepared By Vijay Solanki
iv) Parabolic signal:
Periodic waveforms are the most common of all the waveform types as it includes Sine
Waves.
 The AC (Alternating Current) mains waveform in your home is a sine wave and one
which constantly alternates between a maximum value and a minimum value over time.
The amount of time it takes between each individual repetition or cycle of a sinusoidal
waveform is known as its "periodic time" or simply the Period of the waveform.
In other words, the time it takes for the waveform to repeat itself.
Then this period can vary with each waveform from fractions of a second to thousands of
seconds as it depends upon the frequency of the waveform. For example, a sinusoidal
waveform which takes one second to complete its cycle will have a periodic time of one
second. Likewise a sine wave which takes five seconds to complete will have a periodic
time of five seconds and so on.
So, if the length of time it takes for the waveform to complete one full pattern or cycle
before it repeats itself is known as the "period of the wave" and is measured in seconds, we
can then express the waveform as a period number per second denoted by the letter T as
shown below.
Basic Electronics By Vijay Solanki
Page 18
Basic Electronics (Chapter_01)
Prepared By Vijay Solanki
Relationship between Frequency and Periodic Time
v)Triangular signal:
Triangular Waveforms are generally bi-directional non-sinusoidal waveforms that
oscillate between a positive and a negative peak value.
Although called a triangular waveform, the triangular wave is actually more of a
symmetrical linear ramp waveform because it is simply a slow rising and falling voltage
signal at a constant frequency or rate.
The rate at which the voltage changes between each ramp direction is equal during both
halves of the cycle as shown below.
Basic Electronics By Vijay Solanki
Page 19
Basic Electronics (Chapter_01)
Prepared By Vijay Solanki
vi)Saw tooth signal:
Saw tooth Waveforms are another type of periodic waveform.
As its name suggests, the shape of the waveform resembles the teeth of a saw blade.
Saw-toothed waveforms can have a mirror image of themselves, by having either a slowrising but extremely steep decay, or an extremely steep almost vertical rise and a slowdecay as shown below.
Basic Electronics By Vijay Solanki
Page 20