Lecture 01-02 EEN13401 Networks and Systems.pdf

EEN13401 NETWORK & SYSTEMS
Prepared by:
Dr. Vishal Kumar Gaur
Dr. Arvind Kumar Prajapati
Lecture 01 & 02

Network Classification & Signals:
Unit step, ramp, impulse signals.
LTI system differential equations, responses to inputs.
Network Theorems:
Thevenin’s, Norton’s, Superposition, Reciprocity, Compensation.
Graph Theory:
Graph of a network, Tree, Co-tree, Link, Basic loop and cut set.
Matrices: Incidence, Cut set, Tie set.
Duality, Loop and Nodal analysis methods.
2
Syllabus
EEN13401: Network and Systems

Laplace Transform:
Initial/Final Value Theorems, solving differential equations.
Transform impedance, transfer functions, impulse response.
Poles and Zeros:
Stability, Bode plots, frequency vs. time response.
Two-Port Networks:
Parameters (z, y, h, g), ladder networks, T-M transformation.
Positive Real Functions:
Synthesis of LC, RL, RC circuits (Cauer and Foster forms).
3
Syllabus

Text/Reference Books:
1. Networks & Systems, D. Roy Choudhary, New Age International, 2nd
Edition, 2013.
2. Network Analysis and Synthesis, A. Chakrabarti & S. Bhadra, McGraw
Hill Education, 1st Edition, 2009.
3. Network Analysis, M. E. Van Valkenberg, 3rd Edition, Prentice Hall of
India, 2014.
4. Engineering Circuit Analysis, William H. Hayt & Jack E. Kemmerly,
McGraw-Hill Book Company Inc, 8th Edition, 2013.
4
Books

MST: 25
EST: 50
Sessional: 25 (Quiz/Class Test: 15 + Assignment: 05 + Attendance: 05)
Total = 25 + 25 + 50 = 100
Attendance: 75% attendance is compulsory.
5
Mark Components and Weightage

6
Introduction to Course
Networks: These are electrical circuits or interconnections of
components like resistors, capacitors, inductors, and sources.
Systems: These are physical or logical entities that process signals
to produce meaningful output.

7
In electronics engineering:
A signal carries information.
A system manipulates that signal to produce a desired response.

8
What is Signal?
A signal is the function of one or more independent variables that
carries some information to represent a physical phenomenon.
Examples:
ECG, Voltage across a resistor, Temperature over time, Blood
pressure, etc.

9
Elementary Signals
Step function
Impulse function
Ramp function

10
Unit Step function
A unit step signal is a basic signal that suddenly turns ON at time t =
0 and stays ON (value = 1) forever.

11
Unit Impulse function
The unit impulse signal is a signal that has infinite height, zero
width, but an area of 1, and occurs exactly at t = 0.

12
Ramp function
A ramp signal is a signal that increases linearly with time, starting
from zero.

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 Circuit and Basic Elements
 We are often interested in transferring signal or energy from one point to another.
 Electrical energy is transferred by flow of charge or electrons in a closed path.
 This closed path is called electric circuit.
 To transfer the electrical energy from source to load, there are many equipment interconnected.
 These equipment or components are known as electric circuit elements.
Faculty: Dr. Vishal Kumar Gaur

14
To transfer the electrical energy from source to load, there are many equipment or elements are
interconnected.
Electrical circuit elements can be classified into three broad categories:
1. based on the behaviour described in terms of terminal voltage and current.
Linear Elements
Non-linear Elements
2. based on the capability of element to absorb or generating the electrical energy or electricity.
Active Elements
Passive elements
3. based on the polarity of current conduction
Unilateral Elements
Bilateral elements

15
Electrical Circuit Elements
A. Linear elements
A circuit element is linear if the element’s excitation (input) and response (output) have linear
relationship.
For element to be linear, it must have the properties of Superposition and Homogeneity.
+ -
v
i  Element is subjected to current i and provides the
voltage v as output.
 Superposition: i1 v1
i2 v2
Then, i1 + i2 v1 + v2
 Homogeneity: i v Then, k.i k.v
B. Non-linear elements
Elements do not satisfy the condition of linear elements fall in the category of non-linear elements.
Generic model of element

16
 Which of the following elements are linear?
+ -
v=Ri
i
(a)
(a)
+ -
v=i2
i
(b)
+ -
v=di/dt
i
(c)

17
A. Active elements
Active elements are capable of producing or generating energy. These are thus source of energy.
B. Passive elements
The element which receives energy or absorbs the energy and either converts it into heat or stored in an
electric or magnetic field called passive element.

18
Voltage source and Current source
i. Voltage sources - keep their terminal voltage very nearly the same as their internal voltages (V ≈ E).
ii. Current sources - keep their terminal currents very nearly the same as their internal currents (I ≈ IS).
Equivalent circuit of
practical voltage source
Equivalent circuit of
practical current source
+
-
E
V
Rse
Rsh
IS
I
A. Active elements
Characteristic of current
source
Characteristic of voltage
source
+
-
E
V
Rse
Rsh
IS
I
In ideal
condition:
Rse = 0
Rsh = ∞

19
Active elements or sources can be further sub-categorized as:
i. Independent sources - the terminal voltage (or current) would depend only on the internal source
quantity, but not on any other circuit variable.
ii. Dependent sources - a dependent voltage source (or current source) would have its terminal
voltage (or current) depend on another circuit quantity such as a voltage or current.
Independent
source
Dependent
source
A. Active elements

A. Active elements
20
+
-
+
-
V V=k.ix
I I=k.ix
+
-
V=k.vx I=k.vx
Independent
Voltage Source
Independent
Current Source
Current dependent
Voltage Source
Voltage dependent
Voltage Source
Current dependent
Current Source
Voltage dependent
Current Source
 There can be two types of independent sources
and four types of dependent sources

A. Active elements
21
 Dependent sources are useful in modelling elements such as transistors, operational amplifiers, and
integrated circuits, etc.
 Dependent sources are usually designated by diamond-shaped symbols.
 Voltage source comes with polarities (+ -) in its symbol, while a current source comes with an arrow,
irrespective of what it depends on.

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B. Passive Elements
 The most of the passive elements are the resistance, inductance, and capacitance.
 Passive elements do not generate (or convert from non-electrical energy) any electricity.
 They consume the energy (or convert from electrical form to a non-electrical form such as heat or light),
or store the energy (in electrostatic or electromagnetic fields).
R L C

23
/21
A. Bilateral Elements
3. based on the polarity of current conduction.
 Bilateral circuit elements allow the flow of current in both directions.
 Property of such elements does not affected from the direction of current flowing through it and voltage
polarity applied across it.
B. Unilateral Elements
 Unilateral circuit elements allow the flow of current in one direction only.
 When the polarity of the power supply voltage changed or reversed, either it opposes the flow of current
or shows a different property, i.e., change in resistance value.
 The Diodes, Silicon Controlled Rectifiers (SCRs) are examples of unilateral elements.
 The resistance and impedance properties of the unilateral elements vary so much with the varying of
current direction.
R
L
C
Resistor Diode

Thank You
24
Faculty: Dr. Vishal Kumar Gaur

Lecture 01-02 EEN13401 Networks and Systems.pdf

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