Basic of electronics & BJT

8/7/2019 Basic of electronics & BJT

1/33

BASICS OF

ELECTRONICS&

BJT


2/33

CONDUCTOR

An electrical conductoris a material which

contains movable electric charges.

In metallic conductors, such as copperor

aluminum, the movable charged particles

are electrons. Positive charges may also be mobile in the

form ofatoms in a lattice that are missing

electrons (known as holes), or in the form of

ions, such as in the electrolyte of a battery.


3/33

USES OF CONDUCTOR

To make metallic contacts in various

fabricated components

To make conducting wires


4/33

INSULATOR

Electrical insulation is the absence ofelectrical

conduction Insulators are characterized by having a large

band gap.

Electronic band theory (a branch of physics)

predicts that a charge will flow whenever thereare states available into which the electrons in a

material can be excited.

This allows them to gain energy and therebymove through the conductor (usually a metal).

If no such states are available, the material is

an insulator.


5/33


6/33

SEMICONDUCTOR

A semiconductoris a material with

electrical conductivity due to electron flow

(as opposed to ionic conductivity)intermediate in magnitude between that of

a conductorand an insulator. This means

a conductivity roughly in the range of 103

to 108 siemens per centimeter


7/33

USES OF SEMICONDUCTOR

To make power device components

They are used in active devices and fabricatio


8/33

Intrinsic semiconductor

An intrinsic semiconductor, also called an

undoped semiconductorori-typesemiconductor, is a pure semiconductor

without any significant dopant species present.

In intrinsic semiconductors the number ofexcited electrons and the number ofholes are

equal: n = p.


9/33

PURE SEMICONDUCTOR BEHAVIOUR


10/33

In semiconductorproduction, doping is the

process of intentionally introducing impurities into

an extremely pure semiconductor to change its

electrical properties.

The impurities are dependent upon the type ofsemiconductor. Lightly- and moderately-doped

semiconductors are referred to as extrinsic .

A semiconductor doped to such high levels that iacts more like a conductor


11/33

DOPING

During doping, impurity atoms are introduced to

an intrinsic semiconductor.Impurity atoms act as either donors or

acceptors to the intrinsic semiconductor,

changing the electron and hole concentrations

of the semiconductor


12/33

N -TYPE P -TYPE


13/33

N-type semiconductors

In n-type semiconductors, electrons are themajority carriers and holes are the minority

carriers

N-type semiconductors are created by dopingan intrinsic semiconductor with donor impurities


14/33


15/33

DIODE

In electronics a diode is an electronic device that

restricts current flow chiefly to one direction.The term usually refers to a semiconductor diode,

the most common type today, which is a crystal of

semiconductorconnected to two electrical terminals


16/33

FORMATION OF P-N JUNCTION DIODE


17/33

DIODE IN FORWARD BIAS CONDITION

DIODE IN REVERSE BIASED CONDITION


18/33

When it is forward biased (the higher potential is

connected to the anode lead), it will pass current.

When it is reversed biased ( the higher potential

is connected to the cathode lead), current flow is

blocked

The diode is a device formed from a junction of

n-type and p-type semiconductor material.

The lead connected to the p-type material iscalled the anode and the lead connected to the

n-type material is the cathode.

In general, the cathode of a diode is marked by asolid line on the diode.

The primary function of the diode is rectification.


19/33


20/33


21/33


22/33


23/33


24/33


25/33


26/33


27/33


28/33


29/33

s


30/33


31/33


32/33


33/33

Thank You

Basic of electronics & BJT

Documents

Transcript of Basic of electronics & BJT