##### 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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Relationship Between Charge Control and Hybrid-Pi Parameters We ll next work out an important relationship between charge control parameters and hybridpi parameters. In Figure 10-5a we see a circuit...

Charge Control Model Examples Next, we ll see how to use the charge control model by working through a number of examples. Example 10.1: Transistor inverter with base current drive In this problem,...

Finding Junction Capacitances from the Datasheet How do we find the values of junction capacitances? Well, we re fortunate if manufacturers data is available. For instance, for the 2N3904 transistor,...

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