Section 3: Test subroutine library reference
S530 Parametric Test System Test Subroutine Library User's Manual
3-66
S530-907-01 Rev. A / September 2015
vgsat
This subroutine measures saturated threshold voltage (V
GSAT
) of a field-effect transistor (FET) at a specified
drain-source current (I
DS
).
Usage
double vgsat(int
d
, int
g
, int
s
, int
sub
, double
ipgm
, double
vlim
, double
vsub
)
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
ipgm
Input
The forced drain current, in amperes
vlim
Input
The drain voltage limit, in volts
vsub
Input
Substrate bias, in volts
Returns
Output
Measured gate-source voltage (V
GS
):
2.0E+21 = Measured voltage (V
GSAT
) is within 98 % of the
specified voltage limit (
vlim
)
Details
This subroutine forces gate-source current (I
GS
) and measures V
GS
with the drain shorted to the gate.
If a zero or negative substrate pin is specified, the substrate is left floating. If the pin number is
greater than 0 and VBS is less than 0.9 mV, the substrate is grounded. In all other cases, it is
connected and forced.
A delay is incorporated into the
vgsat
subroutine; this delay is the calculated time required for stable
forcing of
ipgm
within the
vlim
voltage limit.
V/I polarities
N-cIpgm, -V
BS
P-channel -Ipgm, +V
BS
Source-measure units (SMUs)
SMU1: Forces
ipgm
, programmed voltage limit, measures
vgsat
SMU2: Forces V
BS
, default current limit
