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Lecture-01.pdf

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  1. 1. Course code: EEE111 Course Title: Analog Electronics Semester: Spring 2023 Course Teacher Dr. Monir Morshed Professor Email:monir.morshed@northsouth.edu
  2. 2.  A variety of electronic devices used in the design of analog electronics are studied.  Basic understanding of semiconductor devices is covered.  Emphasis is placed on diodes, BJT, and FET.  Small and large signal characteristics and models of electronic devices, analysis and design of elementary electronic circuits are also included.  This course has a mandatory laboratory session (EEE111L/ETE111L – Analog Electronics I Lab) every week Course Contents
  3. 3. Recommended Books Text Book 1. Robert L. Boylestad and Louis Nashelsky, "Electronic Devices and Circuit Theory", 11th Edition, Prentice Hall of India Private Limited. ISBN 81-203-2064-6 Reference 1. Albert Malvino and David J. Bates, “Electronic Principles”, 7th Edition, McGraw Hill. ISBN 978–0– 07–297527–7. 2. Adel S. Sedra and Kenneth C. Smith, "Microelectronic Circuits", 5th/6th Edition, Oxford University Press. ISBN 0-19-514252-7.
  4. 4. Course Objectives 1. Acquire knowledge of electrical characteristics of ideal and practical diodes under forward and reverse bias to analyze and design diode application circuits such as rectifiers and voltage regulators. 2. Utilize operational principles of bipolar junction transistors and field effect transistors to derive appropriate small-signal models and use them for the analysis of basic amplifier circuits. 3. Perform DC analysis (algebraically and graphically using current voltage curves with super imposed load line) and design of CB, CE and CC transistor circuits. 4. Compare and contrast different biasing and compensation techniques and functioning as amplifier.
  5. 5. Course Outcomes COs Description CO1 Illustrate the characteristics of semiconductor devices for determining the device parameters such as resistances, current gain and voltage gain CO2 Apply the pn junction characteristics for the diode applications such as switch, rectifiers, Clippers and Clampers. CO3 Examine DC and AC load line analysis of BJT and FET amplifiers for optimal operating level regardless of input, load placed on the device. CO4 Extend the biasing techniques for bipolar and uni-polar transistor amplifier circuits considering stability condition for establishing a proper operating point. CO5 Utilize low frequency model for estimation of the characteristic parameters of BJT, FET amplifier circuits. CO6 Demonstrate the working principle of special purpose semiconductor diodes and transistors for triggering and voltage regulation applications.
  6. 6. CO with Assessment Methods CO Assessment Method (%) - Attendance 10% CO1-CO6 Class Test/Quiz 20% CO1-CO6 Final Exam 30% C01-C03 Mid Exam 20% C01-C06 Assignment/Presentation 20% C01-C06 Lab Work 0% Any Suggestions?
  7. 7. Analog Electronics Analog Electronics Analog Electronics Electron Mechanics  Flow of Electron in Gas, Vacuum, Semiconductor, etc.  Behavior of Electrons
  8. 8. What is Electronics  Electronics is a branch of physics and electrical engineering  It deals with electrical device and circuits that operate by controlling the flow of electron or other charge particles.  It also deals with how electron behave in semiconductor.  Analog electronics deals with a analog signal whose amplitude can take on any value in a continuous range whereas digital electronics has a digital signal usually take only two levels.
  9. 9. Analog Electronics Active Passive Basic Electronics Components & Devices Measuring Instruments  Rectifiers  Amplifiers  Oscillators  Filters Circuits  Digital Multimeter  Power supplies  Voltage and current source  Oscilloscopes  Function generator  Resistors  Capacitors  Inductors  Diode  Etc.  Transistors  Op-Amps  Etc.
  10. 10. Components & Devices Passive Component:  Passive component is an electronic component which store or absorb energy in the form of voltage or current.  The components which can’t control the flow of current.  Passive component can’t provide any power gain to the circuit.  For example: resistors, capacitors, inductors, and transformers.
  11. 11. Components & Devices Active Component:  Active component is an electronic component which generate energy in the form of voltage or current.  They supply energy to the circuit and they control the flow of current.  Also they can provide any power gain to the circuit.  For example: transistors, Battery, Generators etc.
  12. 12. Circuits  Electrical Circuits: A complete electrical network is an interconnection of electrical components which provide a closed path or loop for current.  Electronic Circuits: It is the combination of electronics component capable of performing computation, amplification, switching, and data transfer.  Analog and Digital Circuits: Analog circuit uses continuous and digital circuit uses discrete signal with fixed number of levels, respectively.
  13. 13. Circuits Series Parallel How it looks Voltage + Current Resistance Features If one components burns current becomes inactive If one components burns current stops only through that branch rest part works well. V V
  14. 14. Circuits Closed Circuits: • A complete electrical circuit through which current can flow when a voltage is applied. • A closed circuit will allow the flow of electricity between power and ground. Open Circuits: • An incomplete electrical circuit through which no current can flow. • Open circuit will break the flow of electricity between power and ground.
  15. 15. Current & Voltage Current: Current is the movement or flow of electric charge. • According to the Ohm’s law current is given by • Measuring unit of current is ‘Amperes (A)’ Voltage: Voltage is the potential difference between two points. • According to the Ohm’s law voltage is given by • Measuring unit of current is ‘Volts (V)’
  16. 16. Matter and Elements • Matter  Occupies space and has weight  The “stuff” that the universe is made of. • Elements  All matter is made up of substances called elements.  which have specific chemical and physical properties.  Cannot be reduced to a simpler substance by chemical reactions.  Over 100 known elements
  17. 17. The Atom All matter is composed of atoms; all atoms consist of electrons, protons, and neutrons except normal hydrogen, which does not have a neutron. Fig.: The Bohr model of an atom -Nucleus • Located at the center of atom • Formed with protons and neutrons -Protons • Positively charged particles -Neutrons • Uncharged particles -Electrons • Negatively charged particles
  18. 18. Electrons and Shells Electrons: • They orbit the nucleus of an atom at certain distances from the nucleus. • Electrons near the nucleus have less energy. Fig.: Illustration of the Bohr model of the silicon atom. Shell: • Each discrete distance (orbit) from the nucleus corresponds to a certain energy level. • In an atom, the orbits are grouped into energy levels known as shells.
  19. 19. Valance Electrons Valence Shell: • The outer most shell • The electrons exist here with the highest energy and are relatively loosely bound to the atom. • Electrons in this shell are called valence electrons. • Valance electrons contribute to chemical reactions and bonding • Valance electrons can break from its atom with gaining sufficient energy from external source.
  20. 20. Ionization Ionization: • Ionization happens when a valance electrons acquires a sufficient amount of energy, called ionization energy, the valance electrons can escape from the outer shell. • The escaped valance electron is called a free electron. • And resulting positively charged atom is called a positive ion. • The atom that has acquired the extra electron is called a negative ion.
  21. 21. Materials in Electronics Conductor: • Material that easily conducts electrical current. • It has large number of free electrons. • such as copper (Cu), silver (Ag), gold (Au), and aluminum (Al), has only one valence electron very loosely bound to the atom. Material Resistivity, ρ (ohm- m) Conductivity σ, ( 𝟏 𝟏) Silver 1.59×10-8 6.29×107 Copper 1.68×10-8 5.95×107 Aluminum 2.65×10-8 3.77×107 Tungsten 5.6×10-8 1.79×107 Iron 9.71×10-8 1.03×107 platinum 10.6×10-8 0.943×107
  22. 22. Materials in Electronics Insulator: • Prevent the flow of electricity under normal conditions. • Valence electrons are tightly bound to the atoms. • There are very few free electrons in an insulator. • Examples of insulators are rubber, plastics, glass, mica, and quartz. Material Insulation Mica High Low Glass Teflon Paper Rubber Air
  23. 23. Materials in Electronics Semiconductor: • Can be altered to function as either a conductor or insulator. • A semiconductor in its pure (intrinsic) state is neither a good conductor nor a good insulator. • Single-element semiconductors are antimony (Sb), arsenic (As), astatine (At), boron (B), polonium (Po), tellurium (Te), silicon (Si), and germanium (Ge). • Compound semiconductors such as gallium arsenide, indium phosphide, gallium nitride, silicon carbide, and silicon germanium are also commonly used. • The single-element semiconductors are characterized by atoms with four valence electrons. Silicon is the most commonly used semiconductor.
  24. 24. Band Gap or Energy Gap • When an electron gets sufficient energy, it can leave the valence shell and jumps to conduction band. The difference in energy between the valence band and the conduction band is called an energy gap or band gap. Energy levels: (a) discrete levels in isolated atomic structures; (b) conduction and valence bands of an insulator, a semiconductor, and a conductor.
  25. 25. Comparison of a Semiconductor Atom to a Conductor Atom • Silicon is a semiconductor and copper is a conductor. • Notice that the core of the silicon atom has a net charge of 4 (14 protons 10 electrons) • The core of the copper atom has a net charge of 1 (29 protons 28 electrons).
  26. 26. Covalent Bonds • Covalent bonding is strengthened by the sharing of electrons. • This bond is a neutrally charged chemical bond.
  27. 27. Covalent Bonds Covalent bonding of the silicon atom. Covalent bonding of the GaAs crystal.
  28. 28. Conduction Electrons and Holes An intrinsic (pure) silicon crystal at room temperature has sufficient heat (thermal) energy for some valence electrons to jump the gap from the valence band into the conduction band, becoming free electrons. Free electrons are also called conduction electrons. It leaves vacancy in the valence band within the crystal. This vacancy is called a hole. Recombination occurs when a conduction-band electron loses energy and falls back into a hole in the valance band.
  29. 29. Electron and Hole Current In conduction band: The free electrons in the conduction band easily attracted towards positive end, when a voltage is applied, this movement of free electrons create a current is called electron current. Electron current in intrinsic silicon is produced by the movement of thermally generated free electrons. In valance band: In the valence band, holes can be generated due to free electrons. Electrons in the valence band are although still attached to their atoms and are not free to move randomly, however, they can move into a nearby hole with little change in its energy level, thus leaving another hole where it came from. Effectively the hole has moved from one place to another in the crystal structure it is called hole current.
  30. 30. Electron and Hole Current
  31. 31. N-type semiconductor • Tn the intrinsic state semiconductive materials do not conduct current well because of the limited number of free electrons in the conduction band and holes in the valence band. • However, adding impurities to the intrinsic (pure) semiconductive material to drastically increased their conductivity is called doping. • Since, the pentavalent atom gives up an electron, it is often called a donor atom. • Majority carrier is electrons and minority carrier is holes
  32. 32. P-type semiconductor • The p -type material is formed by doping a pure germanium or silicon crystal with impurity atoms having three valence electrons such as boron, gallium, and indium. • Because the trivalent atom can take an electron, it is often referred to as an acceptor atom. • Majority carrier is holes and minority carrier is electrons.
  33. 33. Majority and Minority Carriers In an n-type material the electron is called the majority carrier and the hole the minority carrier. In a p-type material the hole is the majority carrier and the electron is the minority carrier.
  34. 34. PN-Junction and Depletion Region  When a p-type materials are combined with n-type materials, a pn junction forms and a semiconductor diode is created. When p and n type material is combined:  The n region loses a free electron as they diffuse across the junction and combines with a hole.  A positive charge is left in the n region and a negative charge is created in the p region, forming a barrier potential.  This region of uncovered positive and negative ions is called the depletion region due to the “depletion” of free carriers in the region.

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