March 2014
Intermediate to advanced
624 pages
26h 33m
English
The MOS transistor is also called a surface field-effect transistor, since it depends on control of current through a thin channel at the surface of the semiconductor (Fig. 6–10). When an inversion region is formed under the gate, current can flow from drain to source (for an n-channel device). In this section we analyze the conductance of this channel and find the ID – VD characteristics as a function of gate voltage VG. As in the JFET case, we will find these characteristics below saturation and then assume ID remains essentially constant above saturation.
The applied gate voltage VG is accounted for by Eq. (6–28) plus the voltage required to achieve flat band: