Electronics and Communication Engineering - Microwave Communication - Discussion

46. 

Assertion (A): PIN diode is used as a fast switch.

Reason (R): PIN diode has very high resistance when reverse biased and very low resistance when forward biased.

[A]. Both A and R are correct and R is correct explanation of A
[B]. Both A and R are correct but R is not correct explanation of A
[C]. A is correct but R is wrong
[D]. A is wrong but R is correct

Answer: Option A

Explanation:

A PIN diode has an intrinsic (i) layer between p and n layers. When reverse bias is applied depletion layers are formed at p-i and i-n junctions.

The effective/width of depletion layer increases by the width of i layer. It can be used as a voltage controlled attenuator.

At high frequencies the rectification effect ceases and impedance of diode is effectively that of i layer.

This impedance varies with the applied bias. It is used in high frequency switching circuits, limiters, modulators etc.


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