EDC CLASS

Diode and its Applications

Dr M Vamshi Krishna

​Diode

A diode is defined as a two-terminal electronic component that only conducts current in one direction (so long as it is operated within a specified voltage level).An ideal diode will have zero resistance in one direction, and infinite resistance in the reverse direction.

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A diode is a semiconductor device that essentially acts as a one-way switch for current. It allows current to flow easily in one direction, but severely restricts current from flowing in the opposite direction

​​Diode Symbol

The symbol of a diode is shown below. The arrowhead points in the direction of conventional current flow in the forward biased condition. That means the anode is connected to the p side and the cathode is connected to the n side.

​Introduction:

​The diode is the simplest and most fundamental nonlinear circuit element. Just like resistor, it has two terminals. Unlike resistor, it has a nonlinear current- voltage characteristics. Its use in rectifiers is the most common application.

Physical Structure of a Diode Metal contact p-type silicon Anode n-type silicon Metal contact Cathode Diodes are formed by joining the N-type and P-type semiconductors.

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​We can create a simple PN junction diode by doping pentavalent or donor impurity in one portion and trivalent or acceptor impurity in the other portion of silicon or germanium crystal block.

​TYPES OF DIODES

​Diode is an electronic device which allows current to flow only in one direction The voltage applied to the semiconductor diode is referred to as bias voltage.

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Types of bias voltages:

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Forward Bias

Reverse Bias

​​Forward Bias

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A forward biased diode conducts current in the forward direction.​

• A forward biased diode conducts current as long as a high external bias voltage with correct polarity is applied

• ​Forward bias or biasing is where the external voltage is delivered across the P-N junction diode. In a forward bias setup, the P-side of the diode is attached to the positive terminal and N-side is fixed to the negative side of the battery

​ReverseBias

​Reverse bias usually refers to how a diode is used in a circuit.

If a diode is reverse biased, the voltage at the cathode is higher than that at the anode. Therefore, no current will flow until the electric field is so high that the diode breaks down

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Extremely small current flows through the diode during reverse biasing. The minority carriers are forced towards the junction where they combine and support an extremely small current

​Applications

• ​Rectifier circuits

• Half-wave rectifier

• Full-wave rectifier

• Transformer with a center-tapped secondary winding

• Bridge rectifier

• Clippers

• Clampers ... etc

External Links:

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https://www.youtube.com/watch?v=n0SiQIaitHk

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​https://www.youtube.com/watch?v=Coy-WRCfems&t=314s

Multiple Select

The best answer for this figure

• Diodes

• the white strip is Anode

• consist of n-type and p-type

• These components do not have polarity

Multiple Choice

Select the correct polarity for forward bias

Multiple Select

When a diode is an forward bias, the circuit will..

• The diode is “ON”

• Diode act as a short switch

• Current able to flow in the circuit

• The positive terminal source is connected to the Anode terminal of diode

Multiple Select

When a diode is a reverse bias, the circuit will..

• No current flow

• diode act as an open switch

• the diode in ON state

• terminal positive of supply is connected to the cathode of diode

Multiple Choice

Select the correct location of forward bias and reverse bias on I-V Characteristic Curve figure

• Forward bias- QI, Reverse bias-QII

• Forward bias- QI, Reverse bias-QIII

• Forward bias- QII, Reverse bias-QII

• Forward bias- QIV, Reverse bias-QII

Multiple Choice

Doping of Semiconductors

• materials which can conduct electricity better than insulator, but not as well as conductors.

• The process of adding of a certain amount of specific impurities atoms in the pure semiconductor.

• when 4 electrons in outermost orbit.

Multiple Choice

Anode is _________ Polarity in diodes

• Negative

• Positive

• Ground

• Hot Side

Multiple Choice

What type of semiconductor is this?

• Covalent Bonding

• P-Type

• N-Type

• Instrinsic

Multiple Choice

What type of semiconductor is this?

• N-Type

• Pentavalent

• Covalent Bonding

• P-Type

Multiple Choice

What happen if anode and cathode combine together?

• Extrinsic

• Covalent Bonding

• Doping

• Diode