The diffusion capacitance of a PN junction _______a)decreases with inc...
CD =τ I /n0 VT
Where, I is the current and VT is temperature factor. The diffusion capacitance is directly proportional to current and indirectly proportional to the temperature.
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The diffusion capacitance of a PN junction _______a)decreases with inc...
Introduction:
The diffusion capacitance of a PN junction is an important parameter that describes the dynamic behavior of the junction. It is a measure of how quickly charge carriers can diffuse across the junction when a voltage is applied. This capacitance is influenced by both current and temperature, and its value changes accordingly. In this question, we need to determine how the diffusion capacitance of a PN junction varies with current and temperature.
Explanation:
The diffusion capacitance of a PN junction is primarily determined by the charge carrier density and the width of the depletion region. Let's examine the effect of current and temperature on these factors.
Effect of Current:
As the current through the PN junction decreases, the charge carrier density also decreases. This is because a lower current implies a lower number of charge carriers crossing the junction per unit time. With a decrease in charge carrier density, the diffusion capacitance decreases. Hence, option 'b' is correct.
Effect of Temperature:
With an increase in temperature, the charge carrier density in the semiconductor material increases. This is due to the increased thermal energy that allows more charge carriers to be generated. As the charge carrier density increases, the diffusion capacitance also increases. Therefore, option 'b' is correct.
Conclusion:
From the above analysis, it can be concluded that the diffusion capacitance of a PN junction decreases with decreasing current and increases with increasing temperature. This behavior is in accordance with option 'b'. The diffusion capacitance is a critical parameter to consider in the design and analysis of PN junctions, especially in high-frequency applications where dynamic behavior is important.
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