Diode Applications,
Special Purpose Diodes Presented By :
Huraira Muzafar
Junaid Ahmed
Abdullah Khan
Introduction: Diode
• The diode is the simplest and most fundamental non-linear circuit
element .
• Like a resistor, it has two terminals
• Unlike a resistor, it has a non-linear current voltage
characteristics.
• Its use in rectifiers is the most common application.
Application of diode circuit
Rectifier circuit
• Half-wave rectifier
• Full-wave rectifier
• Bridge rectifier
Rectifier
A rectifier is an device which
converts alternative current into
direct current and this process is
called rectification.
Half Wave Rectifier
It is the simplest type of rectifier, which is made with just one diode.
•When the voltage of the alternating current is positive, the diode becomes
forward-biased and current flows through it.
•When the voltage is negative, the diode is reverse-biased and the current stops.
Full wave rectifier
This rectifier is essentially made of two half-wave rectifiers, and can
be made with two diodes.
1. When the voltage of the alternating current is positive, one of the diodes
become forward biased whereas the other gets reverse biased. Hence, current
flows through the forward biased diode.
2. When the voltage of the alternating current is negative, the previous reverse
biased diode becomes forward biased whereas the other gets reverse biased.
Hence, current flows through the forward biased diode.
Bridge rectifier
A bridge rectifier is an arrangement of four or
more diodes in a bridge circuit configuration
which provides the same output polarity for
either input polarity. It is used for converting a
n alternating current (AC) input into a direct c
urrent (DC) output.
Special Purpose Diodes
It includes the followings
• Zener diodes
• Vericap / Varactor diodes/variable capacitance diode
• Optical diodes
(i) Light emitting diode (LED)
(ii) Photo diode
Zener diodes
A Zener diode is a type of diode that permits
current not only in the forward direction like a
normal diode, but also in the reverse direction
if the voltage is larger than the breakdown
voltage known as "Zener knee voltage" o
r "Zener voltage".
The device was named after Clarence Zener,
who discovered this electrical property.
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ZENER DIODE APPLICATIONS
The zener diode is often used as a type of voltage regulator for pr
oviding stable stable reference voltages.
Varactor Diodes
Vericap or Varactor diode is a type of diode wh
ose capacitance varies as a function of the volta
ge applied across its terminals
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Application
A major application of varactors is in tuning circuits. For
example, electronic tuners in TV and other commercial receivers
utilize
varactors. When use in a resonant
circuit, the varactor act as variable capacitor, thus allowing the
resonant frequency to be adjusted by a variable voltage level,
where the varactor diode provides the total variable capacitance
in the parallel resonant band-pass filter
Optical Diodes
Two types
i) Light Emitting Diode (LED)
ii) Photo Diode
Light Emitting
Diode (LED)
Operates in forward biased, The
light-emitting diode (LED) emits
photons as visible light. It’s purpose is
for indication and other intelligible
displays. Various impurities are added
during the doping process to vary the
color output.
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Applications
•Visual signals where light goes more or less
directly from the source to the human eye, to
convey a message or meaning.
• Illumination where light is reflected from objects to give
visual response of these objects.
• Measuring and interacting with processes involving no
human vision.
• Narrow band light sensors where LEDs operate in a reversebie as mode
and respond to incident light, instead of emitting light
The Photodiode
A photodiode is a semiconductor device that converts light
into current. The current is generated when photons are ab
sorbed in the photodiode. A small amount of current is also
produced when no light is present. Photodiodes may contai
n optical filters, built-in lenses, and may have large or smal
l 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 ar
ea photodiode. A photodiode is designed to operate in rever
se bias.
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Thank You
