PIN diodes are semiconductor devices that can act as variable resistors at radio and microwave frequencies. They are controlled by forward bias current and can be used as attenuators, modulators, and switches. PIN diodes have a P-type semiconductor, an intrinsic semiconductor, and an N-type semiconductor sandwiched together. When forward biased, PIN diodes have a gradual increase in current flow through the intrinsic region, giving a variation in resistance. This property allows them to be used to control large RF signals with smaller DC excitation. Common applications of PIN diodes include RF switching, attenuation, and modulation.

1. SubjectSubject: Microwave: Microwave

2. PIN DIODE INTRODUTION
• PIN diode semiconductor device that operates as a variable resistor at RF and microwave
frequencies. It is a current controlled deuce.
• By controlling forwarded beat current continuously PIN diode can be used as attenuator,
level and amplitude modulator.They are small in size, with high switching speed.
• An Important Characteristic of PIN diode is its ability to control large RF signals while using
much smaller levels of DC excitation.

3. CONSTRUCTION AND WORKING
• Construction of PIN diode is as shown in Figure PIN is a semiconductor diode in which intrinsic
material has been sandwich between P and N type Of semiconductor material and hence it is
named as PIN diode.
• PIN diode A PIN diode acts as variable resistor
FIGURE OF PIN DIODE

4. FORWARE BASE PIN DIODE
• When PIN diode is forward biased, above its knee voltage as well as sudden flow of the current is
not observed.This is due to intrinsic region which is inserted in between P and N type of the
semiconductor material. Slowly current through the PIN diode will increase.
• This gives variation in resistance across the PIN with change in the applied forward biased voltage.
The equivalent circuit of PIN diode when forward biased is as shown in figure.

6. REVERSE BIASED PIN DIODES

8. APPLICATIONS OF PIN DIODE
• PIN diode as switch
• PIN diode as RF attenuators
• PIN diode as RF modulator

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