Section 7: Measuring I-V characteristics of FETs
Model 2450 Interactive SourceMeter® Instrument User's Manual
7-6
2450-900-01 Rev. A / June 2013
Using SCPI commands with the trigger model to set up the test
In this example, the gate voltage steps from 2 V to 5 V in 1 V steps, the drain voltage sweeps from
0 V to 5 V in 51 steps, and the drain current is measured. The current and voltage measurements are
stored in
defbuffer1
, and the Model 2450 trigger model synchronizes the two Model 2450
instruments.
Commands are sent to either the sweeper on the drain (SMU 1) or the stepper on the gate (SMU 2).
Commands for the sweeper are shown with a light gray background, and commands for the stepper
are shown with a darker gray background. Each bulleted item in the Description column describes a
single line of code in the Commands column. The light-brown shaded code represents pseudocode
that will vary depending on the programming environment you use.
Send the following commands for this example application:
SMU 1,
SMU 2, or
pseudocode
Commands
Description
SMU 1
*RST
SENS:FUNC "CURR"
SENS:CURR:RANG:AUTO ON
ROUT:TERM REAR
SOUR:FUNC VOLT
SOUR:VOLT:RANG 20
SOUR:CONF:LIST:CRE "stepVals"
DIG:LINE1:MODE TRIG, OUT
DIG:LINE2:MODE TRIG, IN
TRIG:DIG1:OUT:STIM NOT1
TRIG:DIG2:IN:CLE
TRIG:DIG2:IN:EDGE RIS
•
Reset the instrument.
•
Set to measure current.
•
Set to measure with autorange enabled.
•
Set to rear terminals.
•
Set to source voltage.
•
Set to 20 V source range.
•
Create a source configuration list called
stepVals
.
•
Set digital line 1 to trigger out.
•
Set digital line 2 to trigger in.
•
Set the stimulus for digital line 1 to the
notify1 event.
•
Clear digital line 2.
•
Look for rising edge on line 2.
Pseudocode
for i=2 to 5 do:
•
Set up a
for
loop from 2 to 5.
SMU 1
SOUR:VOLT i
SOUR:CONF:STORE "stepVals"
•
Set the voltage level to the iteration
number.
•
Store the source configuration to
stepVals
.
Pseudocode
end for
•
End the
for
loop.
SMU 1
TRIG:BLOC:CONF:RECALL 1,
"stepVals"
TRIG:BLOC:SOUR:STAT 2, ON
TRIG:BLOC:MEAS 3
TRIG:BLOC:NOT 4, 1
TRIG:BLOC:WAIT 5, DIG2
TRIG:BLOC:CONF:NEXT 6, "stepVals"
TRIG:BLOC:BRAN:COUN 7, 4, 3
TRIG:BLOC:SOUR:STAT 8, OFF
•
Create trigger model block 1 to load
stepVals
at the first index.
•
Create block 2 to turn the output on.
•
Create block 3 to take a measurement.
•
Create block 4 to generate the notify1
event.
•
Create block 5 to wait on digital line 2.
•
Create block 6 to load the next index of
stepVals
.
•
Create block 7 to branch to block 3, 3
times.
•
Create block 8 to turn the output off.
