Vtext2 - Keithley S530 User Manual

Section 3: Test subroutine library reference

vtext2

This subroutine estimates the extrapolated gate-source threshold voltage of a metal-oxide field-effect transistor
(MOSFET) using a modified version of the vtext subroutine method.
Usage
double vtext2(int d, int g, int s, int sub, char type, double vlow, double vhigh,
double vds, double vbs, double ithr, double vstep, int npts, double *slope, int
*kflag)
d
g
s
sub
type
vlow
vhigh
vds
vbs
ithr
vstep
npts
slope
kflag
Returns
Details
This subroutine is a modified version of the

All setup parameters must have the correct sign (polarity)

An initial binary search is done with LPTLib trigi and searchv subroutines

The I -V
DS

The vlow parameter must be algebraically smaller than the vhigh parameter
3-76
Input The drain pin of the device
Input The gate pin of the device
Input The source pin of the device
Input The substrate pin of the device
Type of transistor: "N" or "P"
Input
Input
The start of the gate-source voltage (V
Input
The end of the V
Input Drain voltage, in volts
Input Substrate bias, in volts
Input
Drain-source trigger current (I
Input
V step size, in volts
GS
Input The number of points in the sweep
Output
The calculated transconductance (g
Output Return status flag:

0 = Normal operation

1 = The ithr parameter is too high; indicates that the vlow
parameter is above the voltage threshold (V
constantly decreasing

2 = Did not find peak slope; indicates that the vhigh parameter
was below V

3 = Binary search on V
vhigh parameters were below V
 4 = The type parameter was not specified as "N" or "P"

5 = V
Output The estimated threshold voltage
data is measured at one time (LPTLib sweepv, smeasi)
GS
S530 Parametric Test System Test Subroutine Library User's Manual
binary search, in volts
GS
), in amperes
DS
(maximum slope was the last value)
T
failed; may indicate that the vlow and
GS
step size is 0.0
GS
vtext (on page 3-73) subroutine. The differences are:
) binary search, in volts
GS
)
m
) and the slope is
T
and the device never turned on
T
S530-907-01 Rev. A / September 2015