The width W of the depletion region varies with the applied voltage VD. Therefor

ID: 1932079 • Letter: T

Question

The width W of the depletion region varies with the applied voltage VD. Therefore, the amount of charge stored in the depletion region also varies with bias and can be modeled as a capacitance. The pn junction capacitance Cj = where A is the junction area and = 10-12F/cm is the dielectric permittivity of silicon. If the width of the depletion region is 1 mu m, and the area of the junction is 2 mu times 5 mu, what is the capacitance (in units of femto-farads, fF)? Is the junction capacitance greater when VD