Lecture 18 - EE IV - PERFORM Alumni

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Nov 15, 2013 (3 years and 6 months ago)

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Lecture 18:

Electrical Engineering IV

EEN 112: Introduction to
Electrical and Computer
Engineering

Professor Eric Rozier, 4/17/13

THERMIONIC TRIODES

The Thermionic Triode


Invented in 1906 by
Robert von
Lieben


Two important
applications:
Amplification, switching

Amplification

Amplification


Switching is a special form of amplification.


Amplification


See a signal? Turn it up
proportionally


Switching


See a signal? Turn it up to the max, no
matter what it is!

Switches enable some important
things…

Thermionic Triodes


Direct heating of the
cathode produces an
electron charge. The
stream is then attracted
to the negatively
charged cathode.


Applying negative
charge to the control
grid isolates the anode
from the cathode.

Thermionic Triode


Amplification of the
signal on the grid.


Switching by setting the
charge on the grid.

The problem with vacuum tubes…


Draw a lot of power


Big


Hot


Fail a lot

SEMICONDUCTORS

Free electrons?

Holes?

The most important invention of the
20
th

century…


John Bardeen, William Shockley, and
Walter
Brittain

are working with
amplifiers.


Found a silicon one that wouldn’t
work. Later made the same
device out of Germanium


Bardeen discovered electrical
current traveled in different ways
through the crystal.


Theorized if they could control
the properties in the crystal
surface, they could control the
flow of electrons.

Theory of Superconductivity

The Transistor


A semiconductor device used to amplify or
switch electronic signals and electrical power.


Composed of semiconductor material with at
least three terminals,
BASE, COLLECTOR,
EMITTER.

The transistor is the fundamental building block
of all modern electronic devices.

Bipolar Transistor

PNP

NPN

Bipolar Transistor

P
ointing
i
N

P
roudly

N
ot
P
ointing
i
N

PNP

NPN

Bipolar Transistor

Field Effect Transistor


The BJT (Bipolar Junction Transistor) relies on
the contact of two types of semiconductors
for its operation.


The FET (Field Effect Transistor) uses an
electric field to control the shape (and
conductivity) of a channel in a single type of
charge carrier.

Field Effect Transistor

Field Effect Transistor


Gate


Source


Drain

Field Effect Transistor

Field Effect Transistor

Transitors


BJT was most commonly used from 1960


1970. Remains the transistor of choice for
many analog circuits.


FETS used in most integrated circuits.

What does this show?

p
-
channel

n
-
channel

Fabrication

Fabrication

Fabrication

Fabrication

Moore’s Law

Moore’s Law

The complexity for minimum component costs has increased at a
rate of roughly a factor of two per year... Certainly over the short
term this rate can be expected to continue, if not to increase.
Over the longer term, the rate of increase is a bit more
uncertain, although there is no reason to believe it will not
remain nearly constant for at least 10 years. That means by
1975, the number of components per integrated circuit for
minimum cost will be 65,000. I believe that such a large circuit
can be built on a single wafer
.

-

Gordon Moore

Moore’s Law