AN2657

Model description and parameter extraction

5/18

Nonlinear current generator

to calculate the static and dynamic current of the device. Moreover, the static current is

required to define the working region of the MOS.

Table 1 reports all the parameters required to extract the equations of the current generator.

To get the generator current equation, a set of equations must be defined. An important

parameter to consider is the threshold voltage of the device shown in Equation 2.

Equation 2

Moreover, a new threshold voltage formula is necessary to describe the weak and strong

inversion region in a single equation (Equation 3).

Equation 3

To describe both regions, a new gate voltage can be defined as in Equation 4.

Equation 4

Table 1.

Parameters required for the extraction of the current generator equations

Name

Description

VT0

Threshold voltage [V]

ETA

KP0

THETA

VGTHETA

Mobility degradation exponent [-]

THETA2..9

XN

DEL

Body effect linearization coefficient [-]

DELVG

L0

Critical length [m]

L

Channel length [m]

EPS

Output conductance factor if L0>L [m]

KE

Output conductance factor if L0<L [Vm]

DT_KP

Mobility thermal coefficient [-]

DT_VT

V

TH

V

T0

η V

DS

DVVT

T

T

NOM

–

()

⋅

+

⋅

–

=

-

VR

V

TH

2XNU

TH

⋅⋅

–

=

U

TH

KT

⋅

q

--------------

=

V

gg

V

TH

2XNU

TH

e

V

gs

VR

–

2XN

U

TH

⋅

⋅

-------------------------------------

⋅⋅

⋅

+

V

gs

⎩

⎪

⎨

⎪

⎧

=