Section 3: Test subroutine library reference
S530 Parametric Test System Test Subroutine Library User's Manual
3-70
S530-907-01 Rev. A / September 2015
Example
vp1(d, g, s, sub, ids, vdlim, vg1, vg2, iglim, &iflag, &vp)
Schematic
vt14
This subroutine estimates the extrapolated threshold voltage (V
T
) of a metal-oxide field-effect transistor
(MOSFET) using a simple two-point technique.
Usage
double vt14(int
d
, int
g
, int
s
, int
sub
, double
vlow
, double
vhigh
, double
vds
,
double
vbs
, double
ithr
, double
niter
)
d
Input
The drain pin of the device
g
Input
The gate pin of the device
s
Input
The source pin of the device
sub
Input
The substrate pin of the device
vlow
Input
The start of the gate-source voltage (V
GS
) binary search, in volts
vhigh
Input
The end of the V
GS
binary search, in volts
vds
Input
The forced drain voltage, in volts
vbs
Input
Substrate bias, in volts
ithr
Input
The targeted drain current (I
DS
), in amperes
niter
Input
The number of iterations in the search
Returns
Output
The extrapolated threshold voltage
Details
This subroutine does a binary search on V
GS
to locate the target threshold current using the vtati
subroutine. This current is I
D1
. I
D4
is then calculated as 4 * I
D1
. A binary search is done again on V
GS
to
find I
D4
. A linear least-squares (LLSQ) line is fit between these two points, and the V
T
parameter is
estimated.
A typical value for
niter
is 10 iterations. If
niter
is less than 2, a value of 2 is used. If it is greater
than 16, a value of 16 is used.
