1. PPT Based on Analog electronics -I
Introduction to Electronic materials include:
Conductors: have low resistance which allows electrical current flow
Insulators: have high resistance which suppresses electrical current flow
Semiconductors: can allow or suppress electrical current flow

2. Conductor
Good conductors have low resistance so electrons flow through them with ease.
Best element conductors include:
Copper, silver, gold, aluminum, & nickel
Alloys are also good conductors:
Brass & steel
Good conductors can also be liquid:
Salt water

3. The atomic structure of good conductors usually includes only one electron in their outer shell.
It is called a valence electron.
It is easily striped from the atom, producing current flow.
Copper Atom
A presentation of eSyst.org

4. Insulators
Insulators have a high resistance so current does not flow in them.
Good insulators include:
Glass, ceramic, plastics, & wood
Most insulators are compounds of several elements.
The atoms are tightly bound to one another so electrons are difficult to strip away for current flow.
A presentation of eSyst.org

5. Overview Introduction What are P-type and N-type semiconductors??
What are Diodes?
Forward Bias & Reverse Bias
Characteristics Of Ideal Diode
I – V Characteristics of Diodes
Rectifiers

6. Introduction
Semiconductors are materials whose electrical properties lie between Conductors and Insulators.
Ex : Silicon and Germanium

7. What are P-type and N-type ?
Semiconductors are classified in to P-type and N-type semiconductor
P-type: A P-type material is one in which holes are majority carriers i.e. they are positively charged materials (++++)
N-type: A N-type material is one in which electrons are majority charge carriers i.e. they are negatively charged materials (-----)

8. Diodes
Electronic devices created by bringing together a p-type and n-type region within the same semiconductor lattice. Used for rectifiers, LED etc

9. Diodes
It is represented by the following symbol, where the arrow indicates the direction of positive current flow.

10. Forward Bias and Reverse Bias
Forward Bias : Connect positive of the Diode to positive of supply…negative of Diode to negative of supply
Reverse Bias: Connect positive of the Diode to negative of supply…negative of diode to positive of supply.

11. Characteristics of Diode
Diode always conducts in one direction.
Diodes always conduct current when “Forward Biased” ( Zero resistance)
Diodes do not conduct when Reverse Biased
(Infinite resistance)

12. I-V characteristics of Ideal diode

13. I-V Characteristics of Practical Diode

14. Rectifiers and its type:
Rectifiers :  rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which is in only one direction, a process known as rectification.

15. Types of Rectifiers Half wave rectifier Full wave rectifier
Center tape full wave rectifier
Bridge rectifier

16. Half wave rectification

17. Working Of Half wave Rectifier
In Half Wave Rectifier one step down transformer & one diode are used. So it convert half wave of a.c into d.c

18. Full wave rectification
For single-phase AC, if the transformer is center-tapped, then two diodes back-to-back (i.e. anodes-to-anode or cathode-to-cathode) can form a full-wave rectifier.

19. Full wave rectifier using transformer and 2 diodes

20. Full wave rectifier using transformer and 2 diodes
In a circuit with a non - center tapped transformer, four diodes are required instead of the one needed for half-wave rectification.

21. Full wave rectifier working animation

22. Working
A bridge rectifier makes use of four diodes in a bridge arrangement to achieve full-wave rectification. It convert both half cycle of a.c into d.c.its efficiency higher then center tape full wave rectifier .

23. Transistors What is a Transistor? History Types Characteristics
Applications

24. What is a Transistor?
Semiconductors: ability to change from conductor to insulator
Can either allow current or prohibit current to flow
Useful as a switch, but also as an amplifier
Essential part of many technological advances

25. A Brief History Guglielmo Marconi invents radio in 1895
Problem: For long distance travel, signal must be amplified
Lee De Forest improves on Fleming’s original vacuum tube to amplify signals
Made use of third electrode
Too bulky for most applications

26. The Transistor is Born
Bell Labs (1947): Bardeen, Brattain, and Shockley
Originally made of germanium
Current transistors made of doped silicon

27. How Transistors Work
Doping: adding small amounts of other elements to create additional protons or electrons
P-Type: dopants lack a fourth valence electron (Boron, Aluminum)
N-Type: dopants have an additional (5th) valence electron (Phosphorus, Arsenic)
Importance: Current only flows from P to N

28. Bipolar Junction Transistor (BJT)
3 adjacent regions of doped Si (each connected to a lead):
Base. (thin layer,less doped).
Collector.
Emitter.
2 types of BJT:
npn.
pnp.
Most common: npn (focus on it).
npn bipolar junction transistor
pnp bipolar junction transistor