S530 Parametric Test System Test Subroutine Library User's Manual
Section 3: Test subroutine library reference
S530-907-01 Rev. A / September 2015
3-71
V/I polarities
N-cV
DS
, +V
G
, -V
BS
, +I
THR
P-channel -V
DS
, -V
G
, +V
BS
, -I
THR
Source-measure units (SMUs)
See the vtati subroutine.
Example
result = vt14(d, g, s, sub, vlow, vhigh, vds, vbs, ithr, niter)
vtati
This subroutine returns the value of the threshold voltage (V
T
) needed to produce a specified drain current (I
DS
).
Usage
double vtati(int
d
, int
g
, int
s
, int
sub
, double
vlow
, double
vhigh
, double
vds
,
double
vbs
, double
ithr
, int
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 voltage (V
GS
) sweep
vhigh
Input
The end of the V
GS
sweep
vds
Input
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
Calculated V
T
:
1.0E+21 = Device triggered on starting voltage
2.0E+21 = Device triggered on end voltage
4.0E+21 = Measured gate current is within 98 % of the 10 µA
current limit
Details
This subroutine executes a binary search on gate-source voltage (V
GS
) to find I
DS
when drain-source
voltage (V
DS
) and substrate bias voltage (V
BS
) are fixed. The number of iterations is programmable.
If a zero or negative substrate pin is specified, the substrate is left floating. If the pin number is
greater than 0 and V
BS
is less than 0.9 mV, the substrate is grounded. In all other cases, it is
connected and forced.
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.
