From Intuitive Analog Circuit Design

Junction Capacitances

In addition to the stored charge in the base region, there is charge stored in the nonlinear baseemitter and base-collector junction capacitances. We ll term these stored charges q ve and q vc, and this corresponds to the large-signal version of the base capacitance C je and feedback capacitance C jc. The extra terms that we need to add to the previous charge control equations are:


The notation SCL refers to the fact that these current components of base and collector currents charge and discharge the space charge layers, also called the depletion capacitances. We ll see how to find these capacitances on a datasheet later on.

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Topics of Interest

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