het214&286_01

HET214 Circuits & Electronics 1 HET286 Circuits & Systems

Review of Circuits Analysis

2Dr. H. S. Chua 2014

Acknowledgement

I thank Prof. Z.H. Man and Prof. C.S. Zhang for sharing their original HET214 and HET286 slides (Hawthorn version) from which these course materials are derived from.


Unit of Study ConvenorDr Chua Hong Siang

Room No. E603

Phone: 082 416353 Ext 7664

[email protected]

HET 214 – Lecturers for Electronics part

Mr Ling Ting SoonRoom No. E617

Phone: 082 416353 Ext [email protected]

A/Prof. Manas K HaldarRoom No. E302

Phone: 082 416353 Ext [email protected]


HET214This unit of study aims to introduce you to the fundamentalconcepts and laws of electric circuit analysis, network theoremsand semiconductor devices.

HET286This unit of study aims to provide you with the fundamentalconcepts and laws of electric circuits including an overview ofsystematic methods and skills required to analyse electric circuits.Your knowledge of the concepts and methods of electric circuitswill be extended to more general dynamical systems. Thelearning in this unit will contribute to 3rd and 4th year units inelectrical, electronic, computer, mechatronic and biomedicalengineering.

The knowledge and analysis methods learnt in this unit will befundamental and important for 3rd and 4th year units in electrical,electronic, computer, mechatronic and biomedical engineering.

Unit of Study Aims


After successfully completing this unit, you should be able to:1. Apply circuit laws and theorems to the analysis of DC circuits

and operational amplifier. (K1, K2, S1, S2)2. Analyse and evaluate the transient and steady state response

of RLC circuits. (K1, K2, S1, S2)3. Apply complex numbers, phasor technique and circuit

theorems to the analysis of steady state AC circuits and AC power calculation. (K1, K2, S1, S2)

4. Design and analyse electronic circuits involving diodes and transistors. (K1, K2, S1, S2)

5. Construct, measure and analyse the response of electrical and electronic circuits. (K1, K2, S1, S2)

6. Report laboratory experiment results. (K1, K2, S1, S2, A2)

HET214 Learning Outcomes


After successfully completing this unit, you should be able to:1. Apply circuit laws and theorems to the analysis of DC circuits,

operational amplifier circuits and transient performance of RLC circuits. (K1, K2, K3, S1, S2)

2. Apply the phasor technique and circuit laws and theorems to the analysis of steady state AC circuits and AC powers. (K1, K2, K3, S1, S2)

3. Apply Fourier series, Fourier transform and Laplace transform to circuit analysis. (K1, K2, K3, S1, S2)

4. Design electric circuits and construct, measure and analyse these circuits. (K1, K2, K3, S1, S2, S3)

5. Report laboratory experiment results. (K1, K2, S1, S2, A2)

HET286 Learning Outcomes


Review of circuit analysis techniques

Network theorems

Response of first-order RC and RL circuits

Sinusoidal analysis

Introduction to Discrete Devices: Diode: VI Characteristics, Diodes applications, Graphical solution of non-linear components, BJ - models, biasing, DC and AC analysis and applications. Frequency response of amplifier circuits

Multi-transistor amplifiers

HET214 Content


Basic concepts, laws and methods for circuit analysis

RLC circuit and transient performance analysis

Phasors and steady state AC circuit analysis including three-phase and magnetically coupled circuits

AC power analysis

Frequency domain response of electrical circuits and systems

Fourier and Laplace transforms and analysis of circuits

Operational amplifier circuit analysis

HET286 Content


K1Basic Science: Proficiently applies concepts, theories and techniques of the relevant natural and physical sciences.

K2 Maths and IT as Tools: Proficiently uses relevant mathematics and computer and information science concepts as tools.

K3 Discipline Specific: Proficiently applies advanced technical knowledge of the specific discipline within that context.

S1 Engineering Methods: Applies engineering methods in practical applications.

S2 Problem Solving: Systematically uses engineering methods in solving complex problems.

S3 Design: Systematically uses engineering methods in design.

A2 Communication: Demonstrates effective communication to professional and wider audiences.

Key Program Outcomes (Swinburne Engineering Competencies) for this Unit of Study

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Assessment Criteria

One 3 hours written final examination (70%-HET214 and 65%-HET286)

Closed book, formulae provided.

Must achieve 35% from the total marks available.

Laboratory Components (30%)

4 laboratory exercises, covering important topics of the course.

A lab report must be submitted 1 week after the laboratory session.

One class test (5%-HET286)

To pass, a candidate must achieve an aggregated marks of 50% or more, and 35% in each major assessment component.

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Laboratories (E503 or E505)

Lab 1 – Week 4

Lab 2 – Week 6

Lab 3 – Week 9

Lab 4 – Week 11

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Review of Circuits Analysis

Electrical Engineering

Circuit analysis

Electric quantities

The ideal basic circuit elements

Sign conventions

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Communication Systems

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Signal Processing Systems

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Control Systems (e.g. Autopilot)

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Generation, Transmission and Distribution of Electric Energy

Multidisciplinary:

Power systems, control systems, telecommunications, computer networks, etc.

Power Systems

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Circuit Analysis

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An electric circuit is a mathematical model that approximates the behaviour of an actual electrical system.But, the term electric circuit is commonly used to refer to an actual electrical system as well as to the model that represents it.Three assumptions permit us to use circuit theory, rather than electromagnetic field theory.

Circuit Analysis

1. Electrical effects happen instantaneously throughout a system

2. The net charge on every component is zero

3. There is no magnetic coupling between the components.

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Circuit analysis is used to predict the behaviour of the electric circuit, and plays a key role in the design process.

Comparison between desired behaviour (design specifications) and predicted behaviour (from circuit analysis) leads to refinements in design.

In order to analyse an electric circuit, we need to know the behaviour of each ideal circuit element (in terms of its voltage and current) and the constraints imposed by interconnecting the various elements.

Circuit Analysis

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Electric ChargeMacroscopically, most matter is electrically neutral most of the time.

Exceptions: clouds in a thunderstorm, people on carpets in dry weather, plates of a charged capacitor, etc.

Microscopically, matter is full of electric charges.Electric charge exists in discrete quantities, integral multiples of the electronic charge 1.6 x 10-19 coulombs

Electrical effects are due toseparation of charge → electric force (voltage)charges in motion → electric flow (current)

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Solids in which all electrons are tightly bound to atoms are insulators.

Solids in which the outermost atomic electrons are free to move around are metals.Metals typically have ~1 “free electron” per atom (~5x1022

free electrons per cubic cm)

Electrons in semiconductors are not tightly bound and can be easily “promoted” to a free state.

insulators semiconductors metals

dielectric materials excellent conductors

Classification of Materials

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Electric CurrentDefinition: rate of positive charge flowSymbol: iUnits: Coulombs per second ≡ Amperes (A)

i = dq/dtwhere q = charge (in Coulombs), t = time (in seconds)

Note: Current has polarity.

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3A-3A

equivalent

The arrow is a fundamental part of the definition of the current

i(t) i(t)

incomplete OKincomplete

Current Notation

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The electromotive force (emf) required to move charge around a circuit OR to move the electron in a conductor.Voltage

Definition: energy per unit chargeSymbol: vUnits: Volts (V)

v = dw/dqwhere w = energy (in Joules), q = charge (in Coulombs)

Note: Potential is always referenced to some point.

Subscript Convention:vab means the potential at a minus the potential at b.vab = va - vb

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If a positive current is entering terminal A (because of external energy source), then terminal A has a higher potential than B or A is positive with respect to B.

+

-

+

-Vba =-5V

-

+Vba = 5V

Rule: Change the polarity, change the sign of voltage

-

+Vab = - 4V

+

-Vab = 4V

A pair of plus-minus signs is part of the definition of any voltage V

Positive Sign Convention

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Suppose you have an unlabelled battery and you measure its voltage with a digital voltmeter (DVM). It will tell you the magnitude and sign of the voltage.

Note that we have used the “ground” symbol ( ) for the reference node on the DVM. Often it is labelled “C” for “common”.

Example 1 – Sign Convention

With this circuit, you are measuring vab.The DVM indicates -1.401, so va is lower than vb by 1.401V.Which is the positive battery terminal?

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A problem like “Find the current” or “Find the voltage” is always accompanied by a definition of the direction:

In this case, if the current turns out to be 1mA flowing to the left, we would say i = -1mA.In order to perform circuit analysis to determine the voltages and currents in an electric circuit, you need to specify reference directions. There is no need to guess the reference direction so that the answers come out positive, however.

Reference Directions

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PowerDefinition: transfer of energy per unit timeSymbol: pUnits: Joules per second ≡ Watts (W)

p = dw/dt = (dw/dq)(dq/dt) = vi

Concept:As a positive charge q moves through a drop in

voltage v, it losses energyenergy change = qvrate is proportional to no. of charges/sec

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Ideal Basic ElementPolarity reference for voltage can be indicated by plus and minus signsReference direction for the current is indicated by an arrow

Attributes:Two terminals (points of connection)Mathematically described in terms of current and/or voltageCannot be subdivided into other elements

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Sign Convention for Power

If p > 0, power is being delivered to the box.If p < 0, power is being extracted from the box.

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P = (2)(3) = 6 W

Determine the power absorbed by each component

P = (4)(5) = 20 W P = -(4)(3) = -12 WP = (4)(-3) =-12 W

Example 2

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SummaryCurrent = rate of charge flowVoltage = energy per unit charge created by charge

seperationPower = energy per unit timeIdeal Basic Circuit Element

2-terminal component that cannot be sub-divideddescribed mathematically in terms of its terminal voltage and current

Passive sign conventionReference direction for current through the element is in the direction of the reference voltage drop across the element

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A high voltage DC transmission line is operating at 800 kV and carrying 1800 A. Calculate the power in megawatts at the Oregon end of the line and state the direction of power flow.

Exercise 1

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One of these cars has a dead battery. The current i is measured and found to be 30 A.a)Which car has a dead battery?b)If this connection is maintained for 1 minute, how much energy is transferred to the dead battery?

Exercise 2

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Textbooks

Alexander, C.K., Sadiku, M.N.O., “Fundamentals of Electric Circuits”, McGraw-Hill, 4th Ed., 2009.

Nilsson J.W., Riedel S.A., “Electric Circuits”, 9th Ed., Prentice Hall, 2011.

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HET 214 Reference Books

Gray ,P. R, Meyer, R. G. (2001). Analysis and Design of Analog Integrated Circuits, John Wiley.

Hambley, R. (1994). Electronics - A top-down approach to computer-aided circuit design. Prentice-Hall.

Horenstein, M.N. (1996). Microelectronic Circuits and Devices, Prentice Hall.

Smith, S. (2010) Microelectronic Circuits, 6th edition. Oxford University Press.

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