Electonics VBR - Notes

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Electronics subject notes for preparation.
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Electonics VBR - Notes

  1. 1. Subject Title : Electronics Prepared by, Vijay Balu Raskar Mr. Vijay Balu Raskar RASKAR (BE)Electrical Engineer Electronics is the branch of engineering. Electonics derived[Type the phone number] from Greek word ‘Elektron and Electron Mechanics’ [Type the fax number] [Pick the date]
  2. 2. Subject Title : ElectronicsPrepared by , Mr. Vijay Balu Raskar vijayraskar2003@yahoo.co.in / vijay.raskar1986@gmail.com_____________________________________________________________________________________ ELECTRONICSS. NO NAME OF CHAPTER MARKS 1 Introduction to electronics 04 2 Semiconductor Theory 10 3 Semiconductor Diode 20 4 Rectifiers Filters and Regulators 20 5 Bipolar Junction Transistor 30 6 Field Effect Transistors 10 7 Integrated Circuits 06 2
  3. 3. Subject Title : ElectronicsPrepared by , Mr. Vijay Balu Raskar vijayraskar2003@yahoo.co.in / vijay.raskar1986@gmail.com_____________________________________________________________________________________ 1. Introduction to electronicsChapter number one is under construction.Refer other chapters because of importance. 3
  4. 4. Subject Title : ElectronicsPrepared by , Mr. Vijay Balu Raskar vijayraskar2003@yahoo.co.in / vijay.raskar1986@gmail.com_____________________________________________________________________________________ 2. Semiconductor TheoryQ.1 Define semiconductor.Ans:- The material whose electrical conductivity lies between those ofconductors and insulators and hence negative temperature coefficientof resistance are known as semiconductors.Q.2 Write a short note on semiconductor.Ans:- They are classified as,There are two types of semiconductor,1) Intrinsic semiconductor and2) Extrinsic semiconductor a) P-type and b) N-typeExplanation:-  The material whose electrical conductivity lies between those of conductors and insulators and hence negative temperature coefficient of resistance are known as semiconductors.  Semiconductors have low conductivity of order of 10 7 s/m.  They have low resistivity of the order of 10 1 to 10 2 ohm-m.  There is low forbidden energy gap (Eg = 1eV).  Resistance of semiconductor material decreases with increase in temperature.  They have moderate concentration of free electrons. 4
  5. 5. Subject Title : ElectronicsPrepared by , Mr. Vijay Balu Raskar vijayraskar2003@yahoo.co.in / vijay.raskar1986@gmail.com_____________________________________________________________________________________  At room temperature, they act as a moderate conductor of electricity.1) Intrinsic Semiconductor:-  A semiconductor in an extremely pure form is known as intrinsic semiconductor.  An intrinsic semiconductor also called an undoped semiconductor or i-type semiconductor.  Intrinsic Semiconductor has a negligible conductivity at room temperature.  Semiconductor material with larger impurity concentrations (Example silicon and germanium)  The current which will flow in an intrinsic semiconductor consists of both electron and hole current.  In intrinsic semiconductors the number of excited electrons and the number of holes are equal: n = p.Conduction in Intrinsic Semiconductor:-  Current conduction is takes place by electron and holes. 5
  6. 6. Subject Title : ElectronicsPrepared by , Mr. Vijay Balu Raskar vijayraskar2003@yahoo.co.in / vijay.raskar1986@gmail.com_____________________________________________________________________________________  The free electrons are generated due to the breaking up of some covalent bonds by thermal energy.  The electron experiences the force towards the positive terminal of the battery.  The holes experience the force towards the negative terminal of the battery.  Random motion of electrons and holes occur a net movement called drift.  This random motion is not contributing to any electric current.  The free electron drifts towards the positive terminal of the battery and holes towards the negative.  This moment of charge carriers constitute the electric current.  Electron flows from negative to positive terminal of the battery.  Current flows from positive terminal to negative terminal of the battery.  The total current inside the semiconductor crystal is the sum of electric currents due to the free electrons and holes.  When the flow of charge carriers is due to an applied voltage the resultant current is called a drift current.  Diffusion current is also exit by the difference of carrier concentration from one region to another.  The current which will flow in an intrinsic semiconductor consists of both electron and hole current. 2) Extrinsic Semiconductor:- 6
  7. 7. Subject Title : ElectronicsPrepared by , Mr. Vijay Balu Raskar vijayraskar2003@yahoo.co.in / vijay.raskar1986@gmail.com_____________________________________________________________________________________  Electrical conductivity have to be increased by adding a certain amount of desired impurity atoms to intrinsic semiconductor is called as extrinsic semiconductor.  The process of deliberately adding or diffusing impurity atoms to the intrinsic semiconductor crystal is called doping.  7

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