1. Zener diodes are used for voltage regulation.
2. Varactor diodes are used for communication tuning circuits.
3. Light Emitting Diodes (LED) convert electrical energy to light energy.
4. Photo diodes convert light energy into electrical energy.
5. Schottky diodes are used in high frequency applications due to their fast switching.
6. Tunnel diodes exhibit negative resistance and are used in oscillators and microwave amplifiers.
1. Zener diodes are used for voltage regulation.
2. Varactor diodes are used for communication tuning circuits.
3. Light Emitting Diodes (LED) convert electrical energy to light energy.
4. Photo diodes convert light energy into electrical energy.
5. Schottky diodes are used in high frequency applications due to their fast switching.
6. Tunnel diodes exhibit negative resistance and are used in oscillators and microwave amplifiers.
1. Zener diodes are used for voltage regulation.
2. Varactor diodes are used for communication tuning circuits.
3. Light Emitting Diodes (LED) convert electrical energy to light energy.
4. Photo diodes convert light energy into electrical energy.
5. Schottky diodes are used in high frequency applications due to their fast switching.
6. Tunnel diodes exhibit negative resistance and are used in oscillators and microwave amplifiers.
1. Zener diodes are used for voltage regulation.
2. Varactor diodes are used for communication tuning circuits.
3. Light Emitting Diodes (LED) convert electrical energy to light energy.
4. Photo diodes convert light energy into electrical energy.
5. Schottky diodes are used in high frequency applications due to their fast switching.
6. Tunnel diodes exhibit negative resistance and are used in oscillators and microwave amplifiers.
Download as PPTX, PDF, TXT or read online from Scribd
Download as pptx, pdf, or txt
You are on page 1of 40
MULTIPLEXER
Multiplex many into one
It is the process of transmitting a large number of information over a single line MUX Combinational Logic circuits Data selector It selects one of many inputs and steers the information to the output by properly selecting the selection (control) lines 2 INPUT MULTIPLEXER (2X1); (2:1) 4 INPUT MULTIPLEXER (4X1) 8 INPUT MULTIPLEXER (8X1) 8 INPUT MULTIPLEXER (8X1) DEMULTIPLEXER demultiplex one into many It is the process of taking information from one input and transmitting the same over one of several outputs DEMUX Data Distributor It is logic circuit that receives information on a single input and transmit the same information over one of several output lines by properly selecting the selection lines 1X2 - DEMUX 1X8 - DEMUX Thank you Positive Clamper Positive Clamper A Positive diode clamper inserts a Positive DC level in the output waveform.
During the ve half-cycle of the input voltage, the
diode is forward-biased, allowing the capacitor to charge to a value near the peak of the input (V p(in) 0.7) [because of the voltage drop of 0.7 volts that exist in the diode].
During the +ve half-cycle of the input voltage, the
diode is reverse-biased. Vp(in) of the +ve half cycle adds to Vp(in) 0.7volts of the capacitor charge held during the ve half cycle.
The capacitor now discharges through the high
resistance of RL. So Vout will be [Vp(in) 0.7volts] of the ve half cycle plus the Vp(in) of the +ve half cycle.
For good clamping action, the RL.C time constant
should be at least ten times the period of the input frequency. Vout = [Vp(in) 0.7volts] + Vp(in) = 2Vp(in) 0.7volts Negative Clamper Negative Clamper Negative Clamper A -ve diode clamper inserts a -ve DC level in the output waveform.
During the +ve half-cycle of the input voltage, the
diode is forward-biased, allowing the capacitor to charge to a value near the peak of the input -(Vp(in) 0.7) [because of the voltage drop of 0.7 volts that exist in the diode].
During the -ve half-cycle of the input voltage, the
diode is reverse-biased. -Vp(in) of the -ve half cycle adds to (Vp(in) 0.7volts) of the capacitor charge held during the +ve half cycle. Negative Clamper The capacitor now discharges through the high resistance of RL.
So Vout will be -[Vp(in) 0.7volts] of the +ve half
cycle plus the -Vp(in) of the -ve half cycle.
For good clamping action, the RL.C time constant
should be at least ten times the period of the input frequency. Vout = -[Vp(in) 0.7volts] + (-Vp(in)) = -(2Vp(in) 0.7volts) Biased positive clamper Biased positive clamper The circuit of a positively biased clamper is shown in the above figure. During the negative half cycle of the input signal the diode is forward biased and acts like a short circuit. The capacitor charges to Vi + Vs . Applying the KVL to the input side
During the positive half cycle of the input signal, the
diode is reverse biased and it acts as an open circuit. Hence Vs has no effect on Vo. Applying KVL around the outside loop. Biased negative clamper Biased negative clamper
In the positive half cycle C gets charged through D to 10V
(peak of sine wave + 5 V) with the straight plate of C at a higher potential. D Clips the output to a maximum of -5V.
In the negative half cycle D is reverse biased. The output can
reach a minimum of 15V (-VC + negative peak of sine wave). SPECIAL PURPOSE DIODES Zener diodes Varactor diodes Light Emitting diodes Photo diodes Schottky diodes Tunnel diodes Zener diodes
Schematic Symbol of Zener diode
Zener diodes A Zener diode is a PN junction diode that is designed to operate in the reverse breakdown region.
The breakdown voltage of a Zener diode is set
by carefully controlling the doping level during manufacture.
So a Zener diode can be operated in the
breakdown region and finds application in voltage regulator, since the breakdown voltage remains constant over a specified range of reverse current values. This breakdown is called Zener breakdown.
But an ordinary diode cannot be
reused after breakdown in the RB condition.
It becomes damaged and is called
avalanche breakdown.
In FB condition both ordinary and
V-I Characteristics of Zener diode Zener breakdown & Regulation Zener breakdown occurs at low reverse voltages. A Zener diode is heavily doped to reduce the breakdown voltage this causes a very thin depletion region.
As a result, an intense electric field exists within the
depletion region. Near the Zener breakdown voltage(Vz), the field is intense enough to pull electrons from their valence band to conduction band to create a heavy flow of current.
Zener diodes are commercially available with
breakdown voltages of 1.8 volts to 200 volts and mainly finds application as a voltage regulator. Power dissipated (PZMAX) in a Zener diode
PZMAX=IZMAX*VZ Varactor diodes
Schematic Symbol of varactor
diode Varactor diodes
Varactor diodes are also called
variable capacitance diodes.
In varactor diodes the junction
capacitance varies with the reveres bias.
These diodes are commonly used
as electronic tuning circuits in communication systems, Filters Light Emitting diodes Schematic Symbol of LED Light Emitting diodes LED converts electrical energy to light energy .
LED diodes are made of light emitting SC
materials like GaAs, GaP, GaAsP etc.
During FB, the valence electrons are excited
to become conduction (free) electrons.
When recombination takes place, the
recombining electrons release energy in the form of light. Photo diodes Schematic Symbol of photo diode Photo diodes Photo diodes converts light energy to electrical energy.
Photo diodes are reverse biased diodes made of
light emitting materials like GaAs, GaP, GaAsP etc..
When the PN junction is exposed to light, the
reverse current increases with the light intensity.
When there is no incident light, the reverse current
is almost negligible and is called the dark current. Schottky diodes Schematic Symbol of schottky diode Schottky diodes Schottky diode is a metal-SC junction.
It is formed by joining a doped SC
region(usually N-type)with a metal such as gold, silver or platinum. Since it has a metal junction, it provides fast switching and hence used in high frequency applications.
These diodes are also called hot-
carrier diodes Tunnel diodes Schematic Symbol of tunnel diode Tunnel diodes
The tunnel diode exhibits a special characteristic
known as negative resistance.
This feature makes it useful in oscillator and
microwave amplifier applications.
1.Voltage regulator is designed using -------------------
diodes
2.Communication tuning circuits are designed using
----------diodes
3.diodes which converts electrical energy to light
energy is called---------- 4. diodes which converts light energy into electrical energy are called-------- 5.diodes which are used in high frequency applications are called ----------- 6.diodes which are used to design oscillator and microwave amplifier are called-------