Environmental Engineering Reference
In-Depth Information
where is a technology parameter known as the transit time of the diode.
The total capacitance,
is the sum of the diffusion capacitance,
and
the junction capacitance,
that is
1.2.4
Diode Small Signal Model
In the case of reverse bias, the diode can be simply modeled with the
junction capacitance defined by (1.13) and (1.14) or by (1.15) and (1.17),
depending on whether the junction is abrupt or graded.
In the case of forward bias a small signal resistor,
models the current-
voltage relationship. Specifically, from (1.18) we have
The capacitive contribution is taken into account by adding the capacitor
in (1.20) in parallel to
Diode small signal models are depicted in Fig.
4.
1.3 MOS TRANSISTORS
Currently, Metal-Oxide-Semiconductor Field-Effect Transistors
(MOSFETs or simply MOS transistors) are the most commonly used
components in integrated circuit implementations since their characteristics
make them more attractive than other devices such as, for example, BJTs.
