Digital and Analogue Electronics: Concepts, Applications, and Comparisons

This assignment covers various aspects of digital and analogue electronics, including their definitions, characteristics, advantages, disadvantages, and applications. It provides detailed explanations and comparisons between digital and analogue electronic systems, highlighting their uses in different fields such as communication, power management, image processing, and more. The assignment includes illustrations and diagrams to support the concepts discussed, making it a comprehensive resource for students and professionals alike.

ELECTRICAL AND
ELECTRONIC
FUNDAMENTAL

TABLE OF CONTENTS
TASK 1 ...........................................................................................................................................1
A. Ohm's law .........................................................................................................................1
B. Kirchhoff's current and voltage law (KVL and KC) ........................................................2
C. Validation of Kirchhoff's law ...........................................................................................4
D. Thevenin's theorem ...........................................................................................................6
TASK 2............................................................................................................................................9
A. Calculate ...........................................................................................................................9
B. Phasor diagram ...............................................................................................................10
TASK 3..........................................................................................................................................10
A. Semiconductor action .....................................................................................................10
B. Discrete semiconductor devices ......................................................................................13
C. Performance and applications of bipolar junction transistor (BJT) and field effective
transistor (FET) ...................................................................................................................14
TASK 4..........................................................................................................................................14
A. Difference between analogue and digital electronics .....................................................14
B. Truth table for the given combinational circuit ..............................................................15
C. Logic function for each case ...........................................................................................15
D. Digital and analogue electronics .....................................................................................16
E. Applications ....................................................................................................................16
F. Electronics applications in terms of relative advantage ..................................................17

TASK 1
A. Ohm's law
According to the Ohm's law the current (I) flowing through a conductor is directly
proportional to voltage drop (V) through it at constant temperature. The proportionality constant
is defined as the resistance. Thus, the expression of Ohm's law is given by:
V I∝
V/I = R
Where R is constant of proportionality and is known as Resistance.
For different readings of voltage (Volt) and current (Ampere) the when graph is plotted then a
straight line is obtained. The V is plotted on y axis while I is plotted on x axis of the graph. The
slope or gradient of the curve is known as Resistance (R) and its dimensional unit is ohm.
I (Ampere) V (Volt)
0.21 2
0.38 4
0.57 6
0.84 8
0.99 10
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Illustration 1: Circuit diagram

The slope R = V/I. In the figure highlighted slope = 7V / 0.7A = 10 Ohm
Thus, between two points the slope can be calculated as : ΔV / ΔI
Where ΔV is the potential difference between two points and ΔI is the current flowing between
two points. Thus, the slope at point V = 2V and I=0.2A is given by the gradient expression:
R= (2-0) / (0.2-0) = 10 Ohm = Slope of the curve
B. Kirchhoff's current and voltage law (KVL and KC)
KVL:
As per this law, the sum of potential differences in a closed loop must be equal to zero.
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Illustration 2: V-I plot for calculating slope

For example in the circuit given above both 1 and 2 are closed loops. When clockwise path is
followed in loop 1 then we get:
V1 + V2 – Vs = 0
This equation followed when passive sign convention is used.
KCL: This law analyses the current entering and leaving any particular node. The total value of
current at any node is zero.
From the circuit it can be analysed that: I1 – I2 – I3 = 0
The current which enters the node have opposite sign than the currents which are leaving the
node.
Circuit analysis:
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The KVL and KCL can be used to analyse the circuit shown above:
On applying KVL in both closed loops ABDA and BCDB following equations are obtained.
ABDA: V1 +V2 – VS = 0
BCDB: V2 + V4 -V3 = 0
The resistance R2 and R4 are connected in series thus the currents I2 and I4 are equal. Thus,
KCL can be applied at node B only:
I1 - I2 -I3 = 0
These equations can be used to analyse the various node current and voltages.
C. Validation of Kirchhoff's law
In order to validate the Kirchhoff's law the above discussed circuit can be simulated and
then verified by using constructing circuit on breadboard and then measuring its values.
The value so resistors is measured by using multimeters and is obtained as:
R1 = 6.75 KΩ
R2 = 2.193 KΩ
R3 = 9.85 KΩ
R4 = 0.994 KΩ
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By KCL:
1166.3 – 196.11 – 970.11 = 0
(All values of current are measured in micro ampere). In order to find the voltage across each
resistor Ohm's law can be applied to the resistors. Similarly, by KVL in closed loops it is
observed that :
7.87 + 2.12 – 10 = 0.002
1.93 + 0.195 – 2.12 = 0.000
Thus, from this simulation Kirchhaff's law are verified.
The verification can also be performed by measuring the values of components on breadboard
implementation. 10V Supply is used on board and following values of components are measured.
V1 V2 V3 V4 I1 I2 = I4 I3
7.37 V 1.80 V 2.62 V 0.87 V 1.08 mA 0.81mA 0.25 mA
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On putting these measured values in the above analysed equations of KVL and KCL following
equation is obtained:
7.37 + 1.80 – 10 = -0.82 (Loop 1)
1.80 + 0.87 – 2.62= 0.05 (Loop 2)
KCL : 1.06 – 0.81 – 0.25
Thus, from the above approaches the Kirchhaff law can be validated.
D. Thevenin's theorem
This theorem states that any linear network can be replaced with its equivalent circuit
consisting of voltage source and single resistance. The theorem is greatly useful to simplify and
analyse the complex circuits by converting them into a simple one. In order to find the Thevenin
equivalent circuit following steps must be followed:
 Load resistor is removed and from open circuit voltage is calculated which is called
Thevenin voltage Vth.
 To determine the equivalent Thevenin resistance (Rth) all voltage sources are shorted and
current sources are opened.
 Equivalent Thevenin circuit can constructed by connecting Vth and Rth in series. The
load resistance RL is connected across open terminals of this equivalent circuit to so that
voltage, current and power can be calculated across it.
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The load resistance is 40 thus it is removed and other voltage sources are short so that Rth can be
calculated.
Rth = (R1*R2) / (R1 + R2)
R1 = 20 Ω and R2= 10Ω so
Rth = 6.67 Ω
The Vth can be calculated as :
I = V/R = (20-10)/(20 +10) = 0.33A
Vth = V across 20 Ω resistor
= 20 – (20*0.33) = 13.33 Volt
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The Thevenin equivalent circuit is given as:
Current through the circuit = I= (13.33)/ (6.67+40)
= 0.29 A
Thus, for the analysis of circuits which have variable load this theorem is helpful for the
simplification purpose.
TASK 2
A. Calculate
L = 80 mH = 0.08 H
R = 200 Ω
C = 22 uF
Source current (Is) = 40 mA = 0.04 A
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Frequency = 50Hz
Solution:
Inductive reactance (XL) = 2пfL = 2п * 50 * 0.08 = 25.12 Ω
Capacitive reactance (XC) = 1/ (2пfC) = 1 / (2п * 50 * 22* 10^(-6)) = 144.75 Ω
Voltage across resistor (Vr) = Is * R = 0.04 * 200
= 8 V
Voltage across capacitor (VC) = Is * XC = 0.04 * 144.75
= 5.79 V
Voltage across inductor (VL) = Is * XL = 0.04 * 25.12
= 1.004 V
Impedance (Z) = [(R^2) + (XL – XC)^2]½
= [(200^2) + (25.12 – 144.75)^2]½
= 233.04 Ω
Supply voltage (Vs)= Is * Z = 0.04 * 233.04
= 9.32 Volt
Current flowing through the circuit = Vs/Z = 9.32 / 233.04
= 39.9 mA
Phase angle (ф)
Cos ф = R /Z = 200 / 233.04
Cos ф = 0.858
ф = 30.9 degree (Lagging)
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B. Phasor diagram
TASK 3
A. Semiconductor action
The semiconductor actions can be demonstrated by evaluating the working principle of
following devices.
Diode:
A diode is a semiconductor device which conducts in one direction only. Thus, when the
polarity of biasing is reversed its current flow characteristics are also changed. The
semiconductor diode consist of p type and n type semiconductors which forms a junction called
p-n junction. P type semiconductor are formed by doping trivalent impurities like Al, Ga are
used while for making n type semiconductor pentavalent impurities such as phosphorus and As
are used. When p-n diode is forward biased then holes from p side and electrons from n side are
moved towards junction and thus a depletion layer is formed. This depletion layer prevents the
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further diffusion of the majority carriers and forward bias current is obtained. On the other hand
when diode is reverse bias the current flow is caused by minority carriers only.
Zener diode
This diode works in reverse bias mode and is used widely as a voltage regulator. When
this diode is forward biased then, it operates similar to a normal diode. On the other hand when
reverse voltage is applied below the specific voltage level called Zener breakdown voltage then
the breakdown of the diode occurs and excessive current flows through the circuit. Due to this
action it provides safety to the circuit connected on its terminal and are widely used for
regulation and protection purpose. These diodes have high level of doping. Though breakdown
phenomenon is also observed in normal diodes but their knee voltage is not as much sharp as of
Zener. Ordinary diodes are not used to operate in breakdown area because it can damage the
entire circuit. When reverse bias is increased in this diode then, the avalanche breakdown takes
place which help to give high value of current in breakdown region.
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Illustration 3: P-N junction semiconductor diode

Transistor as switch
In common emitter (CE) configuration, transistor (BJT) can be used as a switch. In CE
connection input supply is given on base terminal while the load is connected withs collector
terminal. When base voltage is zero then the transistor acts an open switch because collector
current become zero and hence Vout is equivalent to Vcc. Similarly, when specific Vin is
applied the flow of base current cause collector current to increase. The higher value of collector
current cause transistor to undergo into saturation region. The zero output voltage and higher
value of collector current make transistor to serve as closed switch. The base terminal regulates
the current flow from emitter to collector and makes transistor open or close as a switch.
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Illustration 4: V-I characteristics of Zener diode

B. Discrete semiconductor devices
Discrete semiconductor devices are known as the device which consist of only one active
or passive element. These devices cannot be divided into separate functional units. The most
widely used discrete devices are as follows:
Diode: These unidirectional devices are used as voltage regulator, rectifier, signal mixer and
modulator because of their functionality to carry current in one direction only.
Transistor: The transistor are the integral component of electronic devices. They are mainly used
for switching, amplification, logic gates, oscillators and other triggering functions.
Trigger device: The devices like Schmitt trigger are used to control and regulate the power
supply so that another electrical circuits can be operated as per desired functionality.
TRIAC (Triode for AC): It finds its applications in mainly switching and power control
applications. It is also used in designing choppers, speed control devices as well as phase
controlling.
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Illustration 5: Transistor as a switch

C. Performance and applications of bipolar junction transistor (BJT) and field effective transistor
(FET)
BJT:
It is a bipolar transistor in which both majority and minority carriers contributes to
output. Both NPN and PNP transistor can be used as individual components as well as in
integrated circuits. This current controlled device is used to amplifying signals as well as to
perform switching function.
FET:
In FET gate terminal controls the dimension of channel so that movement of charge
carriers from source terminal to drain can be regulated. It is operated by voltage and is
characterised by high value of input impedance. Due to low power requirements the device is
extensively used in IC technology.
TASK 4
A. Difference between analogue and digital electronics
Analogue electronics Digital electronics
It deals with continuous analogue signals. Discrete or digital signals are used.
Less accurate and precise More accurate and precise
Can be easily fabricated on PCB. Difficult to assemble on printed circuit board
due to large size.
Encryption or coding is not possible. Encryption is possible so that data security can
be enhanced.
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B. Truth table for the given combinational circuit
Let the input signals are denoted by A and B then the expression for the output signal Y is given
by:
Y = (A+B)' = A' B'
A B Y
0 0 1
0 1 0
1 0 0
1 1 0
C. Logic function for each case
 The NAND gates used in level 1 acts as inverter or NOT gate. Thus, with inputs A and B
at level 1 inverted output A' and B' are received.
(A.A)' = A'
Similarly, (B.B)' = B'
 At level 2 A' and B' are input to NAND gate. On simplifying the output expression A+ B
is obtained which denotes the logical OR function.
(A'.B')' = A'' + B'' = A+B
 The final output y is the inverted value of expression obtained in level 2. Thus,
Y = (A+B)' = A'B'
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D. Digital and analogue electronics
Analogue electronics
Advantage  Signals can be routed directly without determining their value
periodically.
 Higher degree of precision as compare to digital electronics
Disadvantage  Noise
 Power loss during transmission of signal
 Scalability and storage limitations
Digital electronics
Advantage  Error free transmission
 The information processed can be easily stored.
 More accurate as compare to analogue electronic devices.
Disadvantage  Consumes more energy
 Less suitable for integrated circuit due to higher requirements of
heat management
E. Applications
Analogue electronics: For the applications such as transmission of power and higher information
content requires the use of analogue electronic devices due to the complexity of the information
transmitted. Thus, the applications with power management systems and frequency mixing
requires this type of electronic devices.
Digital electronics: These devices provide versatility in various manufacturing processes by
providing machine control, data acquisition and monitoring methods. The biomedical
applications which require image processing techniques also use digital electronic devices for
obtaining the higher degree of precession.
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F. Electronics applications in terms of relative advantage
Digital circuit based devices:
The ability of digital circuits to encode and decode signals with encryption makes them
highly suitable in applications related to communication and networking. The applications
involving signal processing are also performed with the help of digital processing techniques
because of their wide range of benefits. They are also used in devices such as computers, laptops
and mobile phones due to their encryption feature and high storage facility.
Analogue devices: The tendency to deal with the high power outputs and applications makes
analogue circuits such as filters, rectifiers suitable for the use as an integrated circuit. The
operational amplifiers, switching and amplification purpose such as in music system or
communication devices. Another key application of analogue electronic devices is in power
distribution, filtration and signal mixing operations.
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