Transistors

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2 Νοε 2013 (πριν από 3 χρόνια και 5 μήνες)

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Transistors

• History

• Transistor Types


BJT
: A
bipolar (junction)
transistor

is a three
-
terminal electronic device
constructed of doped
semiconductor material and
may be used in amplifying
or switching applications



FET :
The
field
-
effect
transistor

(FET) relies on
an electric field to control
the shape and hence the
conductivity of a channel of
one type of charge carrier in
a semiconductor material



Power

transistors

What is a Transistor?


A Transistor is an
electronic device

composed of layers of a
semiconductor

material which regulates
current or

voltage flow and acts as a
switch or gate

for electronic circuit.

History of the Transistor

John Pierce

supervised the Bell
Labs team which built the first
transistor (1947)

First Solid State Transistor


(1951) Gordon K. Teal (left) and
Morgan Sparks at Bell
Laboratories, 1951


Akio Morita, who founded a new
company named Sony Electronics
that mass
-
produced tiny
transistorized radios (1961)


Processor development followed
Moore’s Law

Applications

Switching

Amplification

Oscillating Circuits

Sensors

Composed of N and P
-
type
Semiconductors

• N
-
type Semiconductor has an excess of
electrons



Doped with impurity with more valence
electrons than silicon





P
-
type Semiconductor has a deficit of electrons
(Holes)



Doped with impurity with less valence
electrons than silicon


P
-
N Junction (Basic diode):


-

Bringing P and N Semiconductors in contact







P Type




N Type

-

Creation of a Depletion Zone

Reverse Biased
=> No Current

Applying

Voltage to Anode
increases

Barrier Voltage & Inhibits
Current Flow


Applying Voltage to Cathode




Barrier Voltage to Anode allows
current flow

Forward Biased
=> Current

Types Of Transistors

NPN
:

transistor where
the majority current
carriers are electrons

The majority current carriers in the
PNP
transistor are holes

Transistor Operation

California Test Questions

A transistor circuit is used as an
amplifier. When a signal is applied to
the input of the transistor, the output
signal is


A
a smaller amplitude.


B
an equal amplitude.


C
a larger amplitude.


D
zero amplitude.

C: The collector
and emitter will
amplify the
output signal
from the Bias
input.

California Test Questions

A transistor is classified as a
semiconductor because:


A
the transistor conducts electricity.


B
the transistor increases the amplitude.


C
the transistor increases the frequency.



D
intentionally introducing impurities into an
extremely pure

silicon or germanium.


D intentionally introducing
impurities into an extremely pure

silicon or germanium.


Summary

Transistors are composed of three parts


a
base, a collector, and an emitter .

Semi
-
conductive materials are what make the
transistor possible .

There are two main types of transistors
-
junction
transistors and field effect transistors.

Field effect transistor has only two layers of
semiconductor material, one on top of the other