Hello fellows, I hope you all are doing great. In today’s tutorial, we will have a look at Introduction to PIN Diode. There are numerous types of diodes is used such according to their specifications such as Zener diode, Schottky diode, Varactor diode, LED, etc. Like all these diodes there is a diode used for special purposes called PIN Diode. Normal PN junction diode has two regions first is N and second is P but this diode has three regions or layers. PIN diode has three regions first is N or P third is also N or P in between N or P there is a pure semiconductor material. This central layer is of intrinsic material of germanium or silicon.
The central layer also operates like an insulator and current does not flow through it. The other two N and P regions are highly doped to operate like ohmic contact. In today’s post, we will have a detailed look at its working, features, applications and some related parameters. So let’s get started with Introduction to PIN Diode.
Introduction to PIN Diode
- The PIN diode type of diode that has three layers contrary to other diodes. In a center pure layer of semiconductor material and at both ends N or P regions like other diodes.
- If the pin diode is in reverse biasing condition it operates as a constant capacitor.
- In forward biasing conditions, it operates like a current-controlled variable resistor.
- With the decrement of current less forward resistance of a pure or intrinsic part of the diode decreases.
- The relationship between forward series resistance and reverse capacitance characteristics of the PIN diode is shown in the below figure.add picPIN diode characteristics
- This diode operates as a dc-controlled microwave switch activated through the fast variation in biasing.
- As there is no rectification exits at PN junction sp large frequency signal changes to less frequency biasing variation.
- This diode can also be used in attenuation circuitry because the value of its resistance can be changed through the current.
- In telecommunication networks, different types of pin diodes are employed as photodetectors.
PIN Diode Construction
- The structure of a PIN diode is different from the normal diode that it has three layers P and N.
- Among P and N there is a layer of pure or intrinsic semiconductor substance.
- The central region behaves like an insulator and stops the flow of current from N to P or P to N.
PIN Diode Working
- The operation of PIN diode is similar to the normal diode but there are some dissimilarities due to the central intrinsic layer. Let’s discuss working of PIN diode with detail.
PIN Diode Forward Biasing
- When PIN diode is in forward biasing conditions the width fo the depletion region decreases.
- With the decrement in area of depletion region current start to flow through the diode.
- In forward biasing conditions diode operate as a variable resistor.
- In junction of PIN diode, there is an electric field that has large strength due to this speed of transportation of charges increases from P to N region.
PIN Diode Reverse Biasing
- In reverse biasing condition the area occupied by the depletion increases.
- At a specific value of reverse voltage, the complete layer of pure semiconductor substance swept out the charges.
- The value of voltage is known as swept in voltage. The value of swept in voltage is minus two volts.
PIN Diode Applications
- These are some applications of the PIN diode.
RF and Microwave Switches
- For ‘0’ or reverse biasing conditions the capacitance value of a pin diode is less. Due to less capacitance, the radio frequency signal will pass through diode.
- While for forward biasing when a current of one milliampere is flowing the radio frequency resistance for is one ohm that makes it good radio frequency conductor.
- Due to this feature pin diode is fine radio frequency switch.
- Radio-frequency relays can also use as switches but their operation speed is less. While the speed of PIN diode as a switch is high normally one microsecond.
RF and Microwave Variable Attenuators
- With alteration in biasing current of PIN diode there is a possibility to vary the radio frequency resistance of the diode.
- For large frequencies, pin diode operates like a resistor whose resistance value is inversely proportional to the forward current.
PIN Diode as Limiter
- PIN diodes used to provide protection for large frequency testing probes and some related circuitry.
- If the signal strength at input is less the effect of the PIN diode is very less, providing a very less capacitance.
- Different to the rectifier circuit that used diodes PIN diode does not show nonlinear resistance value for radio frequencies.
- If the signal at the input is high pin diode starts its operation as a rectifier, due to forward current drift portion of diode get charged.
Photodetector & Photovoltaic Cell
- The telecommunication system used fiber optics has PIN photodiodes. While operating as photodetector it is in reverse biasing condition.
- For reverse biasing condition diode not operates. When enough amount of light falls on the diode it makes pairs of holes and electrons in a diode.
PIN Diode Advantages
- These are some advantages of PIN diodes that are described here.
- As we discussed that area of the intrinsic region is large due to that large amount of photons fall on the diode.
- Due to the high intensity of light the pairs of electrons and holes increase.
- That increases a large amount of current generation.
- The large area of the intrinsic region decreases the capacitance of the diode. The capacitance of diode is in inverse relation to space between cathodes and anode.
High reverse breakdown voltage:
- The larger area of the depletion region provides a high reverse breakdown voltage. Due to these voltages, this diode is preferred for such circuits where high current can damage circuitry.
PIN Diode Disadvantge
- These are some advantages of pin diodes.
- The reverse recovery time of a PIN diode is high that increases power losses of a diode.
- Current Regulator Diode
- Zener Diode
- Step Recovery Diode
- PIN Diode
- Schottky Diode
- Varactor Diode
- Zener diode Applications
- Laser Diode
So friends that is complete post about PIN diode I hope you have understood each and every parameter related to PIN diode. If you have any queries about it ask in comments. Thanks for reading. See you in the next post have a good day.
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