BSIM3v3.2.2 MOSFET Model - The University of Texas at Dallas

Strong Inversion Drain Current (Linear Regime)where A 0 , A gs , B 0 , B 1 and Keta are determined by experimental data. Eq. (2.4.1)shows that A bulk is very close to unity if the channel length is small, and A bulkincreases as channel length increases.2.5 Strong Inversion Drain Current (LinearRegime)2.5.1 Intrinsic Case (R ds =0)In the strong inversion region, the general current equation at any point yalong the channel is given byI = WC ( V − A V ) vds ox gstbulk ( y) ( y)(2.5.1)The parameter V gst = (V gs - V th ), W is the device channel width, C ox is thegate capacitance per unit area, V(y) is the potential difference betweenminority-carrier quasi-Fermi potential and the equilibrium Fermi potentialin the bulk at point y, v(y) is the velocity of carriers at point y.With Eq. (2.3.1) (i.e. before carrier velocity saturates), the drain currentcan be expressed asµeffE ( y)Ids = WCox ( Vgs −Vth− AbulkV( y))1+E( y)Esat(2.5.2)Eq. (2.5.2) can be rewritten as followsBSIM3v3.2.2 Manual Copyright © 1999 UC Berkeley 2-19