Environmental Engineering Reference
In-Depth Information
The high-frequency model is not easy to determine because the channel is
directly connected to both the source and drain resulting in a distributed RC
network over the whole length of the device. Moreover, because of the
capacitive nature of junction capacitances, the capacitive elements are highly
non-linear. This is another factor making the model quite complicated for
management by hand analysis.
A simplified model, which is quite accurate for small can be
obtained by evaluating the total channel charge contribution and by
assuming half of this contribution to be referred to the source and half to the
drain [7].
Specifically, since the total gate-channel capacitance is given by
gate-source and gate-drain capacitances can be modeled as
where the overlap contribution has been included.
In the same way, the channel-bulk contribution is shared between the
source and the drain thus yielding for
and
the following
