Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
threshold does not depend on the length . This is a quite general statement given in literature but if we keep on reducing the length than it will change . This change can be observed for both length and width.
Eq (1) states that the threshold voltage is only a function of the manufacturing technology and the applied body bias VSB. The threshold can therefore be considered as a constant over all NMOS (PMOS) transistors in a design. As the device dimensions are reduced, this model becomes inaccurate, and the threshold potential becomes a function of L, W, and VDS. Two-dimensional second-order effects that were ignorable for long-channel devices suddenly become significant.
In the traditional derivation of the VTO, for instance, it is assumed that the channel depletion region is solely due to the applied gate voltage and that all depletion charge beneath the gate originates from the MOS field effects. This ignores the depletion regions of the source and reverse-biased drain junction, which become relatively more important with shrinking channel lengths. Since a part of the region below the gate is already depleted (by the source and drain fields), a smaller threshold voltage suffices to cause strong inversion. In other words, VT0 decreases with L for short-channel devices.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
