Question
Download Solution PDFThe capacitance of a p-n junction diode :
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFA diode can have two different capacitances:
Diffusion Capacitance:
It is dominant when the diode is forward and is the result of storage charges when forward biased.
The diffusion capacitance is given by the formula:
\({C_d} = \frac{{{I_{DQ}}\times\tau }}{{2{V_T}}}\) ---(1)
IDQ = Quiescent current of the diode.
τ = Minority carrier lifetime
VT = Thermal voltage
Since the diode current Equation is given as:
\(I_{DQ}=I_S(e^{\frac{qV_f}{kT}}-1)\) ---(2)
From Equation (1) and (2), we conclude that the diffusion capacitance increases exponentially with forward bias voltage (Vf).
Junction Capacitance:
It is dominant when the diode is reverse biased and is the result of the charge stored in the Depletion layer.
The junction capacitance is given by the formula:
\({C_j} = \frac{{A\epsilon}}{W}\)
W = depletion region width
Last updated on May 8, 2025
-> The KVS TGT Notiifcation 2025 will be released for 16661 vacancies.
-> The application dates will be announced along with the official notification.
-> Graduates with B.Ed or an equivalent qualification are eligible for this post.
-> Prepare with the KVS TGT Previous Year Papers here.