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Microwave Communication - Engineering

Q1:

Assertion (A): PIN diode is commonly used for microwave control. Reason (R): A PIN diode uses heavily doped p and n materials.

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

ANS:B - Both A and R are correct but R is not correct explanation of A

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.