Subject Code : ECE – 101/102 BASIC ELECTRONICS COURSE MATERIAL For 1ST & 2ND Semester B.E. (Revised Credit System)

1. Subject Code : ECE – 101/102 BASIC ELECTRONICS COURSE MATERIAL For 1ST & 2ND Semester B.E. (Revised Credit System) DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING

2. BASIC ELECTRONICS BY Mr Jagadish Nayak B.E(E&C),M.Tech (DEAC),MISTE,MBMESI Senior Grade Lecturer Dept of Electronics and Communication Engineering MIT, Manipal

3. Syllabus Module 1. – SEMI CONDUCTOR THEORY Pg. 1 – 26 Module 2. – PN JUNCTION DIODE AND ITS APPLICATIONS Pg. 27 – 49 Module 3. – TRANSISTORS AND APPLICATIONS Pg. 50 – 72 Module 4. – COMMUNICATION SYSTEMS Pg. 73 – 82 Module 5. – OPERATIONAL AMPLIFIERS Pg. 83 – 96 Module 6. – DIGITAL ELECTRONICS Pg. 97 – 131

4. What is an Atom Structure of an Atom Energy Band Theory EV-Unit of Energy Classification of Materials based on Energy Band Theory Properties of Semiconductor Mobility, Current Density, conductivity Intrinsic Semiconductor Electron and hole in Intrinsic semiconductor Conduction by electron and holes Conductivity of a semiconductor Law of Mass action Donor and acceptor impurities Energy band diagram for extrinsic semiconductor Diffusion Drift PN junction PN junction as a diode VI characteristics Module 1 Syllabus of module 1

5. Integrated Electronics Millman Jocobs,Halkies.C.C Electronics Principle Robert boylsted Reference for module 1 :

6. SEMI CONDUCTOR THEORY Introduction We know the importance of using the materials like copper, aluminum etc. in electrical applications. This is because copper, aluminum etc are good conductors. Similarly, some materials like glass, wood, paper etc. Also, find wide applications in electrical and electronic applications. These are called insulators. There is another category of materials whose ability to carry current, called conductivity, lies between that of conductor and insulators. Such materials are known as semi conductors. Germanium and silicon are two well-known semiconductors.

8. The Atom

9. SEMI CONDUCTOR THEORY

14. SEMI CONDUCTOR THEORY neutrons carry no electrical charge at all

15. SEMI CONDUCTOR THEORY The protons and neutrons cluster together in the central part of the atom,called the nucleus, and the electrons 'orbit' the nucleus

16. Electrons carry a negative electrical charge= -1.6x10-19 Coulombs

18. SEMI CONDUCTOR THEORY • Atoms and Elements Ordinary matter is made up of protons, neutrons, and electrons and is composed of atoms. An atom consists of a tiny nucleus made up of protons and neutrons, on the order of 20,000 times smaller than the size of the atom. The outer part of the atom consists of a number of electrons equal to the number of protons, making the normal atom electrically neutral. A chemical element consists of those atoms with a specific number of protons in the nucleus; this number is called the atomic number

19. SEMI CONDUCTOR THEORY The atoms of an element may differ in the number of neutrons; atoms with different neutron numbers are said to be different isotopes of the element. Elements are represented by a chemical symbol, with the atomic number and mass number sometimes affixed as indicated below. The mass number is the sum of the numbers of neutrons and protons in the nucleus.

20. SEMI CONDUCTOR THEORY Constituents of Atoms

21. SEMI CONDUCTOR THEORY

22. SEMI CONDUCTOR THEORY Atomic Structure

23. Atomic Shells The discrete electron levels are arranged in shells. Each shell has a maximum occupancy. The first electronic shell can have at most 2 electrons, the second shell has room for 8 electrons and so on. The 1st shell has the lowest energy. Thus, elements, in their lowest energy state fill the 1st level first, and then fill the 2nd level next. These elements are listed in the 1st and 2nd rows of the periodic table. Atoms are most stable if their outer shell is full. The electrons in outer shells are shielded by the inner shells from the full attraction of the nucleus. These electrons participate most readily in chemical reactions.

24. The Quantum Numbers 1) The Principle Energy Level (cont) Maximum Electron Capacities of the First Four Principle Energy Levels (Shells) n = 4 2n2 = 2 x 42 = 32 electrons n = 3 2n2 = 2 x 32 = 18 electrons n = 2 2n2 = 2 x 22 = 8 electrons n = 1 2n2 = 2 x 11 = 2 electrons 58 electrons The Seventh Level is the Highest Occupied Ground-State Electrons in any Element now Known

25. SEMI CONDUCTOR THEORY Silicon and Germanium Solid state electronics arises from the unique properties of silicon and germanium, each of which has four valence electrons and which form crystal lattices in which substituted atoms can dramatically change the electrical properties.

26. SEMI CONDUCTOR THEORY Silicon In solid-state electronics, either pure silicon or germanium may be used as the intrinsic semiconductor, which forms the starting point for fabrication. Each has four valence electrons, but germanium will at a given temperature have more free electrons and a higher conductivity. Silicon is by far the more widely used semiconductor for electronics, partly because it can be used at much higher temperatures than germanium.

27. SEMI CONDUCTOR THEORY Germanium In solid-state electronics, either pure silicon or germanium may be used as the intrinsic semiconductor, which forms the starting point for fabrication. Each has four valence electrons, but germanium will at a given temperature have more free electrons and a higher conductivity. Silicon is by far the more widely used semiconductor for electronics, partly because it can be used at much higher temperatures than germanium.

28. Silicon Lattice The main point here is that a silicon atom has four electrons which it can share in covalent bonds with its neighbors. These simplified diagrams do not do justice to the nature of that sharing since any one silicon atom will be influenced by more than four other silicon atoms, as may be appreciated by looking at the silicon unit cell.

29. Valence Electrons The electrons in the outermost shell of an atom are called valence electrons; they dictate the nature of the chemical reactions of the atom and largely determine the electrical nature of solid matter. The electrical properties of matter are pictured in the band theory of solids in terms of how much energy it takes to free a valence electron.

30. Electron-volt The electron-volt (symbol eV, or, rarely and incorrectly, ev) is a unit of energy. One electron-volt is a very small amount of energy: 1 eV = 1.60217653(14)×10−19 J. where one electron volt is the energy required to move an electron across a potential difference of one volt.

31. The electronvolt (symbol eV, or, rarely and incorrectly, ev) is a unit of energy. It is the amount of kinetic energy gained by a single unbound electron when it passes through an electrostatic potential difference of one volt, in vacuum. In other words, it's equal to one volt times the magnitude of charge of a single electron. The one-word spelling is the modern recommendation although the use of the earlier electron volt still exists. • One electronvolt is a very small amount of energy: • 1 eV = 1.602 176 53×10−19 J. (Source: CODATA 2002 recommended values)

32. Band theory Electron energy levels in an insulator

33. Energy levels of an atom’s electrons A ball bouncing down a flight of stairs provides an analogy for energy levels of electrons, because the ball can only rest on each step, not between steps. (a) Third energy level (shell) Energy absorbed Second energy level (shell) First energy level (shell) Energy lost Atomic nucleus (b) An electron can move from one level to another only if the energy it gains or loses is exactly equal to the difference in energy between the two levels. Arrows indicate some of the step-wise changes in potential energy that are possible.

34. —18 electrons

35. The Valence Band The valence band is the band made up of the occupied molecular orbital and is lower in energy than the so-called conduction band. It is generally completely full in semi-conductors. When heated, electrons from this band jump out of the band across the band gap and into the conduction band, making the material conductive. The valance band can be seen in the diagram.

36. Conduction Band The conduction band is the band of orbital that are high in energy and are generally empty. In reference to conductivity in semiconductors, it is the band that accepts the electrons from the valence band. The conduction band can be seen in the diagram.

42. Semiconductor Energy Bands For intrinsic semiconductors like silicon and germanium, the Fermi level is essentially halfway between the valence and conduction bands. Although no conduction occurs at 0 K, at higher temperatures a finite number of electrons can reach the conduction band and provide some current. In doped semiconductors, extra energy levels are added. The increase in conductivity with temperature can be modeled in terms of the Fermi function, which allows one to calculate the population of the conduction band.

43. Conductor Energy Bands In terms of the band theory of solids, metals are unique as good conductors of electricity. This can be seen to be a result of their valence electrons being essentially free. In the band theory, this is depicted as an overlap of the valence band and the conduction band so that at least a fraction of the valence electrons can move through the material

44. As long as the current density is totally uniform in the conductor, the uniform resistance R of a conductor of regular cross section can be computed as Where L is the length of the conductor, measured in meters A is the cross-sectional area, measured in square meters  is the electrical resistivity (also called specific electrical resistance) of the material, measured in ohm · meter. Resistivity is a measure of the material's ability to oppose the flow of electric current. Resistance of a conductor

45. A semiconductor has the following prominent properties: Properties of Semiconductors • The resistivity of a semiconductor is less than that of an insulator but more than that of a conductor • A semiconductor has negative temperature coefficient of resistance, i.e., the resistance of a semiconductor decreases with the increase in temperature and vice-versa. For example, Germanium is actually an insulator at low temperature , but it becomes a good conductor at high temperatures. • When some suitable impurity (e.g. Arsenic, Gallium etc.,) is added to a semiconductor, its conducting properties change appreciably

47. Band structure of a semiconductor

50. Silicon Energy Bands At finite temperatures, the number of electrons, which reach the conduction band and contribute to current, can be modeled by the Fermi function. That current is small compared to that in doped semiconductors under the same conditions.