Keithley S530, Руководство пользователя

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S530 Parametric Test System Test Subroutine Library User's Manual Section 3: Test subroutine library reference
S530-907-01 Rev. A / September 2015 3-69
vp1
This subroutine estimates the voltage at which the current flow between the source and drain is blocked
("pinched-off") for a metal-semiconductor field-effect transistor (MESFET) at a specified "pinch-off" current and
drain-source voltage (V
DS
).
Usage
void vp1(int d , int g , int s , int sub , double ids , double vdlim , double vg1 , double
vg2 , double iglim , double *iflag , double *vp )
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
ids
Input
The forced drain current (I
P
), in amperes
vdlim
Input The drain voltage target, in volts
vg1
Input
Start of the gate-source voltage (V
GS
) search, in volts
vg2
Input
End of the V
GS
search, in volts
iglim
Input Gate current limit, in amperes
iflag
Output Return status flag:
0 = Normal completion
1 = Pinch-off voltage (V
P
) is 0.0
2 = Device triggered on starting voltage
3 = Device triggered on ending voltage
Returns Output
Measured V
P
Details
This subroutine is a variant of the
vp
subroutine. The trigger is set to the specified V
DS
and pinch-off
current (I
P
) is forced on the drain. The gate voltage is then searched until the V
DS
value is reached. At
0 V gate-source voltage (V
GS
), the drain voltage is below the specified V
DS
. As V
GS
is increased, V
DS
increases as the device approaches the voltage at which the current flow between the source and
drain is blocked.
If a positive substrate pin is specified, the substrate is grounded. If a positive substrate pin is not
specified, the substrate is left floating.
A delay is incorporated into the
vp1
subroutine; this delay is the calculated time required for stable
forcing of drain-source current (I
DS
) with the V
DS
voltage limit.
V/I polarities
vg1
,
vg2
- Ensures that polarity forward biases the gate-source diode. Starting voltage,
vg1
, must
allow the drain SMU to supply pinch-off current without exceeding the limit.
Source-measure units (SMUs)

SMU1: Forces drain-source current (
ids
), programmable voltage limit, trigger set to V
DS

SMU2: Searches V
GS
, programmable current limit