SEMICONDUCTOR DEVICES
AND MICROELECTRONICS.
Rica Paquio
III- Galileo
Semiconductor Devices and
Microelectronics
Microelectronics
Zener Diode
Diode
Junction Diode
Light Emitting Diode
Photodiodes
Other Diodes

Photodiodes may contain optical filters, built-in
lenses, and may have large or small surface areas.
Photodiodes usually have a slower response time as
its surface area increases. The common,
traditional solar cell used to generate electric solar
power is a large area photodiode.
Photodiode operation


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Small signal or Small current diode - These diodes
assumes that the operating point is not affected
because the signal is small
Large signal diodes - The operating point in these
diodes get affected as the signal is large.
Transient voltage supression diodes - This diode
is used to protect the electronics that are sensitive
against voltage spikes.
Diode Application

Rectification ("frequency shifting")
Typical power supply applications
Half-Wave Rectification
"Figure shows a half-wave rectifier circuit. The signal is exactly
the top half of the input voltage signal, and for an ideal diode
does not depend at all on the size of the load resistor.

"The rectified signal is now a combination of an
AC signal and a DC component. Generally, it is the
DC part of a rectified signal that is of interest, and
the un-welcomed AC component is described as
ripple. It is desirable to move the ripple to high
frequencies where it is easier to remove by a lowpass filter."When diodes are used in small-signal
applications - a few volts - their behaviour is not
closely approximated by the ideal model because
of the PN turn-on voltage. The equivalent circuit
model can be used to evaluate the detailed action
of the rectifier under these conditions.

During the part of the wave when the input is
positive but less than the PN turn-on voltage, the
model predicts no loop current and the output
signal voltage is therefore zero. When the input
exceeds this voltage, the output signal becomes
proportional to, or about 0.6 V lower than the
source voltage."
Full-Wave Retification
Version 1 - Center-Tap Full-Wave Rectifier

Version 2 - Bridge Full-Wave Rectifier
"The diode bridge circuit shown Ö is a full-wave
rectifier. The diodes act to route the current from
both halves of the AC wave through the load
resistor in the same direction, and the voltage
developed across the load resistor becomes the
rectified output signal. The diode bridge is a
commonly used circuit and is available as a fourterminal component in a number of different
power and voltage ratings."
Rectification


A rectifier is an electrical device
that converts alternating current (AC), which
periodically reverses direction, to direct
current (DC), which flows in only one
direction.
The process is known as rectification.
Physically, rectifiers take a number of forms,
including vacuum tube diodes, mercury-arc
valves, copper and selenium oxide
rectifiers, semiconductor diodes, siliconcontrolled rectifiers and other silicon-based
semiconductor switches.
Half-wave rectification[edit]

In half wave rectification of a single-phase supply,
either the positive or negative half of the AC wave is
passed, while the other half is blocked. Because only
one half of the input waveform reaches the output,
mean voltage is lower. Half-wave rectification requires
a single diode in a single-phase supply, or three in
a three-phase supply. Rectifiers yield a unidirectional
but pulsating direct current; half-wave rectifiers
produce far more ripple than full-wave rectifiers, and
much more filtering is needed to eliminate harmonics of
the AC frequency from the output.
Full-wave rectification
A full-wave rectifier converts the whole of the input
waveform to one of constant polarity (positive or
negative) at its output. Full-wave rectification converts
both polarities of the input waveform to pulsating DC
(direct current), and yields a higher average output
voltage. Two diodes and a center tappedtransformer,
or four diodes in a bridge configuration and any AC
source (including a transformer without center tap),
are needed.
Transitor

A transistor is a semiconductor device used
to amplify and switch electronic signals and electrical
power. It is composed of semiconductor material with at
least three terminals for connection to an external
circuit. A voltage orcurrent applied to one pair of the
transistor's terminals changes the current through
another pair of terminals. Because the controlled
(output) power can be higher than the controlling (input)
power, a transistor can amplify a signal. Today, some
transistors are packaged individually, but many more
are found embedded in integrated circuits.

(Assorted
discrete
transistors.
Packages in
order from top
to bottom: TO3, TO126, TO92,SOT-23)