Keithley S530

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-channel +Ipgm, -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