Transcript Presentazione di PowerPoint

Clil Elettronica
Teacher: Anna Settanni
Students:
Roberto Ferri
Daniele Fusaro
William Palmisano
Principal Points
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Introduction
Types of semiconductor diodes
Current–voltage characteristic
Rectifier Bridge
Introduction
In electronics, a diode is a two-terminal
device.
Diodes have two terminals and most of them
are used for their unidirectional electric
current property.
Types of semiconductor diodes
There are a lot of types of
semiconductor diodes for
example the most usefull
are:
• Zener Diode
• Schottky Diode
• Diode Led (light emetting
diode)
• Photodiode
• Varicap
Circuit Simbol
These are some diode symbol:
Diode Led
Diode Zener
Diode Schottky
Diode Varicap/Varactor
PhotoDiode
Current–voltage characteristic
A semiconductor diode's current-voltage characteristic , or
I–V curve, is related to the transport of carriers
through the so-called depletion lover or depletion
region that exists at the p/n junction between differing
semiconductors. When a p-n junction is first created,
conduction band (mobile) electrons from the N-doped
region diffuse into the P-doped region where there is a
large population of holes (places for electrons in which
no electron is present) with which the electrons
"recombine".
Current–voltage characteristic
A diode’s I–V characteristic can be approximated by four
regions of operation.
At very large reverse bias, beyond the peak inverse voltage
or PIV, a process called reverse breakdown occurs which
causes a large increase in current that usually damages the
device permanently. The avalanche diode is deliberately
designed for use in the avalanche region. In the zener
diode, the concept of PIV is not applicable.
Current–voltage characteristic
Rectifier Bridge
A diode bridge or bridge rectifier is an arrangement of four diodes in a
bridge configuration that provides the same polarity of output voltage for
either polarity of input voltage. When used in its most common application,
for conversion of alternating current (AC) input into direct current (DC)
output, it is known as a bridge rectifier. A bridge rectifier provides full-waves
rectification from a two-wire AC input, resulting in lower cost and weight as
compared to a center-tapped trasformer design.
The essential feature of a diode bridge is that the polarity of the output is the
same regardless of the polarity at the input. The diode bridge circuit is also
known as the Graetz circuit after its inventor, physicist Leo Graetz.