Tektronix Keithley SourceMeter 2450 User Manual page 77

Section 7: Measuring I-V characteristics of FETs
-- ######################## 2450 #1 (drain) setup ################
-- Set up the source function.
smu.source.func = smu.FUNC_DC_VOLTAGE
smu.source.ilimit.level = 300e-3
smu.source.autorange = smu.ON
-- Set up the measure function.
smu.measure.func = smu.FUNC_DC_CURRENT
smu.measure.autorange = smu.ON
smu.terminals = smu.TERMINALS_REAR
-- Set up a linear sweep.
smu.source.sweeplinear("MOSFET", 0, 5, num, 0.001)
-- ########################## 2450 #2 (gate) setup ################
-- Set up the source function.
node[2].smu.source.func = node[2].smu.FUNC_DC_VOLTAGE
node[2].smu.source.autorange = node[2].smu.ON
node[2].smu.source.ilimit.level = 100e-3
-- Set up the measure function.
node[2].smu.measure.func = node[2].smu.FUNC_DC_CURRENT
node[2].smu.measure.autorange = node[2].smu.ON
node[2].smu.terminals = node[2].smu.TERMINALS_REAR
-- Turn the stepper output on.
node[2].smu.source.output = node[2].smu.ON
readings = {}
sourcevalues = {}
iteration = 0
steppoints = 4
-- Set the stepper V level, delay, start sweep, and wait to complete.
for i = 2, 5 do
node[2].smu.source.level = i
delay(0.01)
trigger.model.initiate()
waitcomplete()
for j = 1, num do
readings[j+iteration*num] = defbuffer1[j]
sourcevalues[j+iteration*num] = defbuffer1.sourcevalues[j]
end
iteration = iteration+1
end
-- Turn the stepper output off.
node[2].smu.source.output = node[2].smu.OFF
-- Print the formatted readings.
if defbuffer1.n == 0 then
print("\nNo readings in buffer\n")
else
for k = 1, num do
print(string.format("%f\t%f\t\t%f\t%f\t\t%f\t%f\t\t%f\t%f", sourcevalues[k],
readings[k], sourcevalues[k+num], readings[k+num], sourcevalues[k+num*2],
readings[k+num*2], sourcevalues[k+num*3], readings[k+num*3]))
end
end
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Model 2450 SourceMeter® Instrument User's Manual
2450-900-01 Rev. E / August 2019