GATE EC 2015 Set 1 — Question 43
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Electronic Devices → P-N Junction & Diodes → Depletion & Diffusion Capacitance
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Question
The built-in potential of an abrupt p-n junction is 0.75 V. If its junction capacitance () at a reverse bias () of 1.25 V is 5 pF, the value of (in pF) when = 7.25 V is _____.
Correct answer
2.4 to 2.6
Solution
For an abrupt p-n junction, the junction capacitance is inversely proportional to the square root of the total potential across the junction ().
So, , where K is a constant.Given:
= 0.75 V
At = 1.25 V, = 5 pF
We need to find at = 7.25 VFrom the formula:
Divide the two equations:
Substitute the given values:
pFThe value of when = 7.25 V is 2.5 pF.
So, , where K is a constant.Given:
= 0.75 V
At = 1.25 V, = 5 pF
We need to find at = 7.25 VFrom the formula:
Divide the two equations:
Substitute the given values:
pFThe value of when = 7.25 V is 2.5 pF.
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