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Gunn Diode – Gunn Diode Oscillator

Gunn Diodes are named after a researcher J. B. Gunn from an IBM, he discovered that the materials form a group (III-V) of predict table such as Gallium arsenide (GaAs), and Indium Phosphide (InP), when applied voltage increases up to the certain value the mobility of electrons in these materials decreases, thereby producing negative differential resistance region. A diode made up of these materials can generate microwaves frequencies.

What is a Gunn Diode?

Gunn diode is two terminals electronic devices, which is composed of only one type of doped semiconductor i.e N-region. The unique property of Gunn diode is that it works in the Negative differential resistance region, which means it can be used to generate microwaves frequencies of 0 to 100 GHz.

The Gunn Diode is also known as Transferred Electronic Device (TED) because it is composed of N-region, and N-region semiconductor has electrons as a majority carrier, and the Transferred Electronic Devices (TEDs) uses such materials which have electrons in the majority.

Note: A negative differential resistance means the relationship between Voltage and current is out of phase (180°).

Symbol of Gunn Diode:

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There are a number of symbols assigned for Gunn diode that may be seen in different circuit diagrams, one of the most widely used standard symbol for Gunn diode is shown below in which two simple diodes touching at the common point.

Symbol of Gunn Diode

What is the Gunn Effect?

Sir John Battiscombe Gunn (J.B Gunn) in 1963, observed something useful while working on noise properties of semiconductors, he observed that material of group (III-V) of predict table have the ability to generate microwaves frequencies and oscillation. Gunn Effect can be summarized into that whenever the voltage applied to the semiconductor material of group (III-V), increase up to the critical voltage value they generate microwave power of few Gigahertz (GHz).

Construction of Gunn Diode:

The Gunn diode is fabricated from a single N-type semiconductor layer. It has three layers of N-type semiconductor. Most widely used material for the construction of the Gunn diode is Gallium arsenide (GaAs), and Indium Phosphide (InP).

Note: It can also be constructed from other materials of a group (III-V) of predict table.

Among these three layers of the Gunn diode, the first layer and third layer is widely doped of the n-type semiconductor. While the in-between second layer of this Diode is lightly doped compared to 1st and 3rd layer. During the manufacturing process of the Gunn Diode, the first and third layer are formed by the ionization process and the middle layer is an epitaxial layer grown on the N-type substrate.


In order to use this Diode in electronic circuits, the metallic connection in the first and third layer is provided during the manufacturing process.

Note:
• The heat sink is used to make the Diode stable for the excessive heat and to prevent damages.
• The range of generation of microwave frequencies depends on the amount of doping in the first and third layers of the Diode.

Read More: Zener Diode , V-I Characteristics, Working, and Applications

Working of Gunn Diode:

The Gunn diode is unique diode it is different from an ordinary P-N junction diode because there is no P-region and no junction in Gunn Diode. But still, it is called a diode due to the presence of two electrodes in the construction of this Diode. When the external voltage is applied to this diode, the entire voltage appears in the active region. Here active region is referred to as a middle layer of the device.

Due to which the electrons from the 1st layer of the conduction band (having almost zero resistivity) are transferred into the third layer of the valence band. Because applied voltage has made the electrons to flow from conduction band to valence band. The third layer of Gallium arsenide has the mobility of electrons which is less than that of the conduction band of the first layer.

When the electrons have transferred from the conduction band to the valence band, after some threshold value the current through the device starts decreasing, Due to this the effective mass of electrons starts increasing and thus mobility starts decreasing due to which the current starts decreasing, And this creates the negative differential resistance region in the Gunn diode.

In this negative differential resistance region, the current and voltage have an inverse relationship, which means when the current starts to increase the voltage starts to fall. And when voltage starts to increase the current start to decrease. Thus, it generates pulses with 180° phase reversal and thus this device is able for the operation of amplifier and oscillator circuits.

Also See: What is Electronics, History of Electronics, Difference between Electronics and Electrical

Gunn Diode Oscillator

Gunn diodes are widely used as oscillators to generate microwaves with frequencies range of 1 to 100 GHz. It is a Negative Differential Resistance device as explained above and also they are called as transferred electron device oscillator.

There are two types of Gunn Diode Oscillators, TEO oscillators, and Microstrip oscillators.

Gunn Diode Oscillator

When the DC bias is applied to this diode it behaves in negative differential resistance and generates microwave frequencies. Consequently, the circuit provided below is able to oscillate at low frequencies with the presence of tuned circuit inductance and other circuit connections.

Read More: What is the Duty Cycle?

Characteristics of Gunn Diode:

The characteristic of Gunn Diode is almost similar to the tunnel diode characteristics.

The graph below shows the V-I characteristics of a Gunn Diode with the negative differential resistance region.

Initially the Current starts to increase in Gunn diode with the applied bias voltage, At a particular instant, the current starts to decrease and this point is known as peak point. After crossing peak point the current starts decreasing and this creates a negative differential resistance region in the Gunn diode. And because of this negative differential resistance region, the diode acts as the oscillator.

Gunn Diode Operations Mode:


In 1963 the J.B Gunn first declared his observation of microwave oscillator; various modes of operation have been introduced, depending on their operating conditions and material parameters.

Here we will cover the present four modes of operations of the Gunn Diode.

  1. Gunn oscillation mode: in the Gunn oscillation mode, In this region the device is unstable and In this case, the oscillation frequency is almost entirely determined by the resonant frequency of the cavity and has a value of several times the intrinsic frequency.
  2. Stable amplification mode: In the stable amplification mode, Gunn Diode exhibits amplification at the distinct-time frequency rather than the oscillation. This is known as stable amplification mode.
  3. LSA oscillation mode: LSA or Limited-Space-Charge Accumulation mode is the simplest mode of operation, and it consists of a uniformly doped semiconductor without any internal space charges. Due to this, the internal electric field of the device would be uniform to the applied voltage. The current in the device is then proportional to the drift velocity.
  4. Bias-circuit oscillation mode: This mode occurs only when there is either Gunn or Limited-Space-Charge Accumulation oscillation when a semiconductor diode is biased to the threshold; the value of average current in a device suddenly drops as the oscillations begin in Gunn Diode. Due to the drop of the current in diode can lead to oscillations in the bias circuit.

Advantages of Gunn Diode:

  1. Gunn’s are cheaper to construct.
  2. It provides better SNR or Noise to Sound Ratio.
  3. Gun’s are very small in size and rigid in nature.
  4. This diode is applicable to be used for amplification and oscillations.
  5. It can have a good bandwidth of 1 to 100 GHz.
  6. It requires a very low operating voltage.
  7. Oscillator circuit is simple to construct.

Disadvantages of Gunn Diode:

  1. It is thermal sensitive hence require heat sinks.
  2. It is less efficient than other frequency generator devices.

Applications of Gunn Diode:

  1. Gunn’s are used for amplification and oscillation.
  2. These are used as a sensor in the Collision avoidance radar systems in electronic communication.
  3. These are used in Vehicle ABS system.
  4. They are used as Traffic analyzer sensors
  5. They are used in commercial applications of electronic instruments and devices such as, `Blindspot’ car radar, Pedestrian safety systems, Elapsed distance meters, Automatic identification, Presence/absence indicators, Movement sensors, Distance measurements.

This was all about Gunn Diode, Gunn Effect, Construction of Gunn Diode, Characteristics of Gunn diode, Operation Modes of Gunn Diode, Gunn diode oscillator, and its working with applications in brief, and if you have any query or information regarding the Gunn diodes, please commenting below.

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Full Wave Rectifier

FULL WAVE RECTIFIER- Center-Tapped and Bridge Rectifier

welcome to this article, In this article, we are going to learn about FULL WAVE RECTIFIER- Center-Tapped and Bridge Rectifier as we Learned about Half-wave rectifiers previously.

Today we are going to study about Full Wave rectifier and their types. so before going to start let me tell you if you have not learned my article on Half Wave rectifier so you must check out that you will understand the basics of rectifiers circuits. so let’s get started.

What is Rectifier Circuit?

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A rectifier circuit is that circuit which performs conversion of AC voltages to DC Pulsating Voltages. So how this Rectifier Circuit Works? I mean how the Full Wave Rectifier circuits work? and why we use Full Wave Rectifier circuits? let’s start our discussion.

A Half-Wave rectifier has very few applications, But the full wave rectifier is the most commonly used rectifier. why is it so? it is because it is mostly used in every type of dc power supplies.

In this section, you will use the same concepts that you learned previously in half-wave rectification article, we will take that concept and expand it to full-wave rectifier working. You will learn about two types of full wave rectifiers.

  1. Center-Tapped Full Wave Rectifier.
  2. Bridge Full Wave Rectifier.

Working of Full Wave Rectifier:

A Full Wave rectifier allows current in unidirectional (one-way) through the load during the entire of the input cycle, whereas a half-wave rectifier allows current through the load only during one-half of the cycle.

The result of full-wave rectification is an output voltage with a frequency twice the input frequency and that pulsates every half-cycle of the input, as shown in given picture below.
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Full wave rectifier block diagram

The number of +ve alternations that make up the full wave rectified voltage is twice that of the half-wave voltage for the same time interval. The average value, which is the value measured on a dc voltmeter, for a full-wave rectified sinusoidal voltage is twice that of the half-wave, as shown in the following formula:
Full Wave rectifier output voltage

Working of Center-Tapped Full-Wave Rectifier

A Center-Tapped rectifier is a type of full wave rectifier that uses two diodes connected to the secondary of a center tapped transformer, as shown in Figure given below. A Centre Tapped Transformer is one whose secondary number of turns are grounded to provide two isolate circuits in secondary of Transformer.

Mostly the Word Centre Tapped is used whenever the circuit is grounded in its center. The input voltage of  Centre Tapped Full Wave Rectifier is coupled through the transformer to the center-tapped secondary. Half of the total secondary voltage appears between the center tap and each end of the secondary number of turns as shown in given figure.

Center Tapped Full wave rectifier

For a positive half-cycle of the input voltage:

The polarities of the secondary voltages are as shown in Figure (a). This makes forward-biases diode D1 and reverse-biases diode D2. The path for current is through Diode 1 and the load resistor, as indicated.

For a negative half-cycle of the input voltage:

The voltage polarities on the secondary are as shown in Figure (b). This makes reverse-biases D1 and forward-biases D2. The current path is through D2 and RL, as indicated. Because the output current during both the positive and negative portions of the input cycle is in the same direction through the load, the output voltage developed across the load resistor is a full-wave rectified dc voltage, as shown below.

Center Tapped Full wave rectifier

Read More: What is the Duty Cycle?

Effect of the Turns Ratio on the Output Voltage


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The output voltage of a center-tapped full-wave rectifier is always one-half of the total secondary voltage less the diode drop, no matter what the turns ratio.output voltage of Center Tapped Full wave rectifier

Peak Inverse Voltage

PIV for Center Tapped Full wave rectifier

Each diode in the full-wave rectifier is continuously changing from forward-biased and then reverse-biased. The maximum reverse voltage that a diode can handle is the peak secondary voltage Vp(sec). The peak inverse voltage across either diode in a full-wave center tapped rectifier is:

PIV for Center Tapped Full wave rectifier

Working of Bridge Full Wave Rectifier


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The bridge rectifier is a best full wave rectifier which uses four diodes that connected as shown in Figure below. When the input cycle is in going for positive alternation as shown in part (a), the diodes D1 and D2 are in forward-biased and they conduct current in the direction as shown.

A voltage is generated across Load Resistor that looks like the +ve half of the I/P cycle. During this period of duration, diodes D3 and D4 are reverse-biased.

When the input cycle of bridge full wave rectifier is going in the negative cycle as in (b), the diodes D3 and D4 are also going in forward bias and they conduct current in the same direction through Load Resistor as during the +ve half-cycle.

when the negative half-cycle is coming for the diode, D1 and D2 are going in reverse-biased. A full-wave rectified output voltage appears across RL as a result of this action.

Bridge Full Wave Rectifier operation

Bridge full wave rectifier Output Voltage

A bridge rectifier with a transformer-coupled input is shown in (a). During the +ve half-cycle of the secondary voltage, diodes D1 and D2 are forward biased. we are neglecting diode drop here.

The same is true when D3 and D4 are forward-biased during the negative half-cycle.

output voltage of Bridge Full Wave Rectifier

As you can see in Figure (b), two diodes are always in series with the RL during +ve and -ve half-cycles. If these diode drops are taken into account, the output voltage is.

output voltage of Bridge Full Wave Rectifier

Bridge Full Wave Rectifier circuit

Peak Inverse Voltage for Bridge Full Wave Rectifier

Since the output voltage is ideally equal to the secondary voltage, If the diode drops of the forward-biased diodes are included as shown in Figure 2–40(b), the peak inverse voltage across each reverse-biased diode in terms of Vp(out) is

PIV of Bridge Full Wave Rectifier

The Peak Inverse Voltage rating for Bridge Full wave rectifier’s diodes is less than that required for the center-tapped configuration.

If we neglect the diode drop, the bridge rectifier requires diodes with half the PIV rating of those in a center-tapped rectifier for the same output voltage.


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Bridge Full Wave Rectifier

This was all about for FULL WAVE RECTIFIER Center-Tapped and Bridge Rectifier if you like this article then appreciate our efforts by doing comment thanks for visiting. check daily for more best articles relative studies and technology.

Also Read:

  1. A Detailed article on What is PN Junction Diode, Characteristics and Applications.
  2. Well Explained Zener Diode Operations and Characteristics.
  3. What is LED- How Light Emitting Diode Works?
  4. What is Photo-diode- How it works?
  5. Game Changer Tunnel Diode, Working and its Operations.
  6. What is Varactor Diode, How it works?
  7. What is Diode Clipper and How they work?
  8. What is Diode Clamper Circuits and How they Work?
PN Junction Diode

PN Junction Diode, its Characteristics and Applications

PN junction Diode plays a vital role in our electronic fields, because of their unique property (current flows in only one direction) they are used in many electronic or electrical circuits like rectifiers, switches, clippers, clampers, voltage multipliers.

In this article, we will learn about what is a PN Junction Diode and how it Works and also effect on PN Junction diode with different modes and I am sure this article will help you a lot to understand about Diode.

After completing this article you will be able to:

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  • Understand the PN Junction Diode.
  • Understand the Working of PN Junction Diode.
  • Understand the Effect of Forward Bias and Reverse Bias on PN Junction Diode.
  • Understand the V-I Characteristics of PN Junction Diode.
  • Understand the Practical Applications of PN Junction Diode.

What is PN Junction (Diode):

PN Junction Diode is a two-terminal semiconductor device. It’s made up from a small piece of semiconductor material (usually Silicon), it allows the electric current to flow in one direction while opposes the current in other direction. In the Forward Bias, the diode allows the current to flow in uni-direction. On the other hand, when the diode is reverse biased it opposes the electric current to flow. A PN Junction Diode is a semiconductor device with two opposite region such as (P-type region and N-type region).

  • The P-region is called as the anode and is connected to a positive terminal of a battery and it has Holes in majority carrier and electrons in minority carrier.
  • The N-region is called as the cathode and is connected to the negative terminal of a battery and it has Electrons as a Majority carrier while holes as Minority carrier.

When the P-type semiconductor material is joined with the N-type semiconductor material, a P-N Junction is formed, hence resulting P-N Junction is also called as a P-N Junction Diode.

The basic diode structure and symbol of PN Junction Diode is shown in the figure below.

PN Junction Diode

 
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Biasing of Diode:

Biasing means applying external voltages to the device, biasing of a diode is of two types: Forward Biasing and other one is Reverse Biasing.

Forward Biasing of Diode: We connect positive terminal of the battery to the P-type Material and Negative terminal of the battery to the N-type, hence this configuration is called as Forward Bias Configuration of Diode. In this configuration Diode allows the current to flow in uni-direction.

Reverse Biasing of Diode: We connect Negative Terminal Battery to the P-type Material and Positive terminal of Battery to the N-type Material, hence this configuration is called as Reverse Bias configuration of Diode. In this configuration, diode does not allow the flow of current.

Biasing of PN Junction Diode

For More Read: Biasing of Diode [in Detail]

Forward Bias of Diode:

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Forward bias is the condition that allows current through the PN junction Diode. The voltage source is connected in such a way that it produces a Forward Bias. This external bias voltage is designated as V(bias). The resistor limits the forward current to a value that will not damage the diode.

Note that the -ve side of VBIAS is connected to the n-region of the diode and the +ve side is connected to the p-region. This is one requirement for forward bias.

A second requirement is that the bias voltage, V(bias), must be greater than the barrier potential.

Forward bias of diode

What is Barrier Potential of PN Junction Diode?


A Barrier Potential is an internal potential a semiconductor material, in case of Silicon-based PN Junction diode it is 0.7v and in case of Germanium, it is 0.3v. It means in order to forward bias the PN junction diode V(bias) should be greater than 0.7 for silicon and 0.3V for germanium.


As we know the N-type material is consist of Electrons and the P-type material is consist of Holes.

A fundamental picture of what happens when a PN junction diode is forward-biased is shown below. When the P-type material is connected with a positive terminal of battery it transfers the holes (positive charge carrier), which travels from p-type material to the N-type material through (Junction).

When the N-type material is connected with a negative terminal of battery it transfers the free electrons (negatively charged carriers), which travels from n-type material to the P-type material through (junction).

These free electrons are attracted towards the positive terminal of the diode while the holes are attracted towards the negative terminal of a diode.

Working of diode
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For More Read: Forward Bias of PN Junction [in Detail]

Reverse Bias of Diode:

Reverse bias is the condition that essentially prevents current through the PN junction diode. As mentioned above if we connect -ve terminal of the battery to P-type material and +ve Terminal of Battery to N-type material this lead to the diode in Reverse Bias. note that the depletion region is shown much wider than in forward bias.

A diode connected for reverse bias. A limiting resistor is shown although it is not important in reverse bias because there is essentially no current.

Reverse Bias of PN junction Diode
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An illustration of what happens when a PN junction diode is reverse-biased is shown below. When the P-type material is connected with a negative terminal of a battery, the holes are attracted away from the junction and attracted to the negative electrodes of batter.

Similary when the N-type material is connected with a positive terminal of a battery, the free electrons are attracted away from the junction and attracted towards the positive electrodes.

This results in an increase in the depletion region. As the depletion region widens, the availability of majority carriers decreases. As more of the n- region and p-regions become depleted of majority carriers, the high potential barrier is created thus opposing electric current to flow in reverse bias.

Effect of deplation region on PN junction Diode

Note: if the reverse bias voltage is increased up to a high value, it will damage the PN junction diode.

V-I CHARACTERISTIC OF A PN junction Diode:

As you have learned, forward bias produces the current through a PN junction diode and reverse bias essentially prevents current, except for a negligible reverse current. Reverse bias prevents current as long as the reverse-bias voltage does not exceed the breakdown voltage limit of the junction. Now we will examine the relationship between the voltage and the current in a diode on a graphical basis.

Read More: What is the Duty Cycle?

Effect of Forward Bias on V-I Characteristics of PN Junction Diode:

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When a forward-bias voltage is applied across a diode, there is current. This current is called the forward current.

When the forward-bias voltage is increased to a value where the voltage across the diode reaches approximately 0.7 V (barrier potential), the forward current begins to increase rapidly, as illustrated in Figure given below. As you continue to increase the forward-bias voltage, the current continues to increase very rapidly, but the voltage across the diode is constant till 0.7v for silicon and 0.3v for germinium.

PN junction diode on forward bias

Effect of Reverse Bias on V-I Characteristics of PN Junction Diode

When a reverse bias is applied across a PN junction diode, there is an extremely small reverse current (IR) through the PN junction due to minority carriers.

Once the applied bias voltage is increased to a value where the reverse voltage across the diode reaches the breakdown value of the diode which is (VBR), the reverse current begins to increase rapidly. As you further increase the bias voltage, the voltage across the diode increases above Breakdown, and diode become damaged, thus it’s not a normal mode of operation for most PN junction devices.

PN junction diode on Reverse bias

Complete V-I Characteristics on PN Junction Diode

Characteristics curve of PN junction diode

Combine the curve for both forward bias and reverse bias, and you have the complete V-I characteristic curve for a PN junction diode, as shown in Figure give below.

Applications of PN Junction Diode:


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  1. PN Junction Diodes are mostly used for rectification (Alternative Current to Pulsating DC).
  2. They are used as clipper to clip the portion of AC.
  3. They are used as clamper to change the reference voltage.
  4. They are used as switches in many electronic circuitry.
  5. They are used in Voltage Multipliers to increase the output voltage.
  6. They are used in power supplies.

There are Many different types of PN Junction Diode, and we have covered all of them check out the  working of different types of diodes:

  1. What is a Zener Diode?
  2. What is LED?
  3. What is PhotoDiode? 
  4. What is Tunnel_Diode?
  5. What is Varactor_Diode?

This is all about PN Junction Diode Working, Operations, and its V-I Characteristics if you like our article or you think you have learned from this PN Junction Diode, its V-I Characteristics please share and comment below. Thanks and Stay connected with Studentsheart.com

Difference between diode and zener diode

Difference Between Diode and Zener Diode (Updated)

A major difference between Diode and Zener Diode is that a PN junction diode can operate in forward bias only whereas a Zener Diode can operate in Forward bias as well as in reverse bias. There are a number of differences between a normal diode and a Zener diode and in this article, we will cover them one by one.

We will cover differences between a Diode and Zener diode with respect to their Symbols, Constructions, Operations, and Applications and after reading this article you will be able to understand all major differences between a Diode and Zener diode.

 

Difference between Diode and Zener Diode

Chart down below shows the difference between Diode and Zener Diode.
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PARAMETERDIODEZENER DIODE
Definition Diode is a semiconductor device which allow current in only one direction.Zener diode is special purpose diode which allows current in forward and reverse bias both.
SymbolDiode symbol (2019)Zener diode
OperationDiode is always operated in forward bias it get damages when operated in reverse bias.Zener diode is special diode it can work in forward bias as well as in reverse bias.
DopingDiode is less doped semiconductor device.Zener diode is 1000 times more doped compared to a diode.
ConductivityDiode is uni-directional device (only allow current in one direction).Zener diode is bi-directional device (can allow current in forward and reverse direction).
Breakdown VoltagesDiode has very low breakdown voltage it can not sustain reverse voltages.Zener diode has high breakdown voltages it can sustain large breakdown voltages.
It ObeyDiode obeys Ohm's LawZener diode does not obey Ohm's Law.
ApplicationsDiode is used in rectification, Clipping, Clamping, Voltage Multipliers, Power supplies, Protection Circuits .etc.Zener diode is mostly used in voltage regulators circuits.

 

What is Diode?


A diode is a semiconductor device which is formed when two alternative semiconductors are joined together i.e. when P-layer of Semiconductor and an N-layer of a semiconductor is joined together a junction is formed called a PN junction also called a Diode.

A diode is a current controlling device which is used to control the current in one direction. It is used for applications like Switching, Rectification, Clipper circuits, Clamper circuits, Voltage multipliers, etc.

The P-layer can be considered as a positive layer because it has holes in the majority whereas N-layer is considered as a Negative layer which has electrons in the majority.

Diode symbol (2018)

A diode is similar to a switch it has two modes of operation. When the diode is forward bias it behaves like a closed switch (ON Switch), and when the diode is reverse bias it behaves like an open switch (Off switch).

When the P-type material is connected with a positive terminal of the battery and N-type material is connected with a negative terminal of the battery then the diode is said to be as Forward bias.

When the N-type material is connected with a positive terminal of a battery and P-type material is connected with a negative terminal of battery then the diode is said to be as Reverse Bias.

During forward bias of the diode, the diode does not conduct immediately, but after a unique forward voltage, it starts to conduct. That forward voltage is commonly known as Diode knee voltage. If the diode is made up of silicon material than the knee voltage is 0.7V and if the diode is made up of germanium then the knee voltage is 0.5v.


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Pn junction diode

During reverse bias of diode, the depletion layer starts to widen. Hence a wide depletion region has more resistance for the movement of majority carries thereby electric conductivity is very low. Therefore; no electric current flows in reverse bias of diode.

 

But the minority carriers can flow during reverse bias condition, constituting a very small current in the diode, that small current is temperature dependent. If the reverse bias increase beyond the value of temperature also increases and the minority carriers also increases, which can cause the diode to damage hence reverse bias condition is not used in diode operation.

Therefore, a diode is always operated in the forward bias mode.

What is Zener Diode?


The Zener diode is a special purpose diode which is always operated in the breakdown region. It has the special ability to allow the current to flow in forward direction as well as in the reverse direction, The Zener diode is highly doped as compared to the normal diode.

Zener diode

In terms of the construction, the Zener diode is constructed similar way as a normal diode is constructed; the only difference in terms of their construction is that a diode is less doped as compared to a Zener diode.
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The Zener diode has two modes of operation, When the Zener diode is forward bias It behaves same like a normal diode after the knee voltage of 0.7V it conducts the current in one direction just a like a normal diode, but when the Zener diode is reverse biased, it operates in breakdown region which means it does not get damaged in reverse bias but it works in reverse bias region which makes this diode bidirectional semiconductor device.

zener diode construction

During the reverse bias of the Zener diode, the depletion layer starts to reduce, because a Zener diode is a highly doped diode hence it has very thin depletion region, hence the electric conductivity is high. When the reverse voltage reached at breakdown region the current start to increase in reverse direction and Thus, a Zener diode behaves as a voltage regulator.

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Key differences Between Diode and Zener Diode


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  1. Normal diode is operated in forward bias, whereas a Zener diode is a special purpose diode which is operated in forward bias and reverse bias.
  2. In terms of their electric current conductivity, a Diode is a uni-directional device which conducts current in only one direction whereas Zener diode is a bi-directional device which can conduct in forward bias as well as in reverse bias.
  3. In terms of their doping, A normal PN junction diode is less doped as compared to a Zener diode whereas Zener diode is highly doped semiconductor diode.
  4. In terms of their breakdown voltage, A normal diode has very low breakdown voltage it can sustain less amount of reverse voltage, whereas A Zener diode has a very high breakdown voltage which means it can sustain greater reverse voltage compared to the normal diode.
  5. In terms of their operation, A normal diode can operate only in forward bias whereas a Zener diode can operate in reverse bias as well in forward bias.
  6. A normal diode is a primary device and a Zener diode is a secondary device by just applying more doping to a normal diode a Zener diode can be obtained.
  7. A normal diode obeys Ohm’s law whereas a Zener diode does not obey Ohm’s law. Hence, a diode is PTC device whereas Zener diode is NTC device
  8. In terms of their applications, A normal diode is used as rectification operation, clipping operations, voltage multipliers, etc. whereas a Zener diode is used as a voltage regulator.

Conclusion


The Diode and Zener diode are different from each other with respect to their symbols, construction, operations, and applications, a major difference between diode and Zener diode is the electric current conduction normal diode can conduct in one direction whereas Zener diode is able to conduct in both forward and reverse direction.
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Another major difference is that normal diode is less doped whereas Zener diode is a highly doped semiconductor.

A normal diode can get damaged in reverse direction but Zener diode is designed to operate in reverse direction.

A normal diode is used for rectification purpose, clipping, clamping and voltage multiplication operations whereas the Zener diode is commonly used for voltage regulation operations.

Diode Clamper- Positive, Negative Clamper Working and Applications

This article is based on the diode clamper circuit, working of positive and negative clamper circuits and the applications of clamper circuits using different waveforms and circuit.

In our earlier articles, we learn about diodes and the working of diodes and the applications of the diode as half wave rectifier, full wave rectifier, clipper circuits. And in this article, we are moving forward to learn about the clamper circuit and their working.

What is the Diode Clamper?

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A Diode Clamper (DC restorer) is a circuit which changes the dc reference of an ac signal. Basically, a clamping diode circuit(or a clamper) essentially adds a d.c. component of the ac signal.

In Diode Clampers it is important to understand that the shape of the original signal is same it is not changed in the output just the reference of waveform is shifted vertically, this is achieved with clamper circuit.

There are two types of Clamper Diode circuits:

  1. Positive Clamper Circuit
  2. Negative Clamper Circuit

Positive Diode Clamper:

If a vertical shift is achieved in Positive direction i.e. if the signal is pushed up so that the negative peaks falls on the zero level then the clamper is called a positive diode clamper.

Negative Diode Clamper:

The negative Diode clamper does the reverse i.e. it pushes the signal downwards so that the positive peaks fall on the zero level.

The following point is important to understand in Diode Clampers:

The clamping circuit does not change the peak-to-peak or r.m.s. value of the waveform. If you measure the input voltage and clamped output with an a.c. voltmeter, the readings will be the same.

 

Working of Positive Diode Clamper:

To understand the working of positive diode clamper we are applying negative half cycle of the input voltage. When the negative input voltage is applied, the diode is forward biased, allowing the capacitor to charge to almost the peak of the input (Vp(in)-0.7). shown in fig (a).


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Positive clamper During negative cycle

Positive Clamper Circuit Diagram

 

Just after the negative cycle, the diode is reverse bias and capacitor which was charged during the negative cycle that has to now discharge. Which means all the voltage will be summed producing double of Vp(in) at load. Here the amplitude is same just output is clamped. i.e if input Vp was 5v then the clamped output is nearly 10 practically (10-0.7), as shown in fig (b).

Positive Clamper Output

Working of Negative Diode Clamper:


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Reverse the diode and apply positive half cycle first, during positive half cycle of input the diode is forward bias and the capacitor is charging up to (Vp(in)-0.7) after the positive cycle when a negative cycle of input is received the diode is reverse bias which means the charged capacitor has to discharge so the voltage will be summed (vp+vc1) and the summed voltage will appear at output (Load resistor).

Hence such type of clamper is known as Negative Diode Clamper which clamps or pushes the output waveform downwards to the reference.

Negative Clamper Circuit

Negative Clamper Circuit

Negative Clamper Output

Negative Clamper Output

Also Read: Difference Between Clipper and Clamper

Video of Clamper Diode Circuit:

Applications of Diode Clamper Circuit:


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  1. Clampers are mostly used in test equipment, sonar, and radar systems.
  2. They are widely used for their common application of voltage doubles or voltage multipliers.
  3. Clampers are mostly used for removing the distortions
  4. In the transmitting and receiving circuitry of television a clamper is used to stabilize to define sections of the luminance signals to preset levels.
  5. Clampers are used to provide protection to the amplifiers from large errant signals.
  6. They are commonly used for the analysis of synchronized signals from the composite visual signals.

This all about Diode Clamper- Positive, Negative Diode Clamper Working Circuits, If you get the concept and learned something new today then do not forget to leave a comment for us and share our work with your friends’ thanks a lot.

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