Tutorial 4: Customizing A User Test Module (Utm) - Keithley 4200A-SCS Reference Manual

Section 8: Keithley User Library Tool (KULT)

Tutorial 4: Customizing a user test module (UTM)

This tutorial demonstrates how to modify a user module using KULT. In the ivswitch project, there
is a test named rdson. The rdson test measures the drain-to-source resistance of a saturated N-
channel MOSFET as follows:
1. Applies 2 V to the gate (V
2. Applies 3 V to the drain (V
3. Applies 5 V to the drain (V
Calculates the drain-to-source resistance rdson as follows:
rdson = (V
The rdson test has a potential shortcoming. If the drain current is noisy, the two current
measurements may not be representative of the actual drain current. Therefore, the calculated
resistance may be incorrect.
In this example, the user module is modified in KULT so that ten current measurements are made at
V and ten more at V
d1
readings at V
The modified test, rdsonAvg, measures the drain-to-source resistance of a saturated MOSFET. The
MOSFET is tested as follows when rdsonAvg is executed:
1. Applies 2 V to the gate (V
2. Applies 3 V to the drain (V
3. Averages the 10 current readings to yield a single reading (I
4. Applies 5 V to the drain (V
5. Averages the ten current readings to yield a single reading (I
6. Calculates the drain-to-source resistance (rdsonAvg) as follows:
rdsonAvg = (V
8-40
) to saturate the MOSFET.
g
) and performs a current measurement (I
d1
) and performs another current measurement (I
d2
-V ) / (I -I )
d2 d1 d2 d1
. The current readings at V
d2
are averaged to yield I
d2
) to saturate the MOSFET.
g
) and makes ten current measurements.
d1
) and makes ten more current measurements.
d2
-V ) / (I -I )
d2 d1 d2 d1
Model 4200A-SCS Parameter Analyzer Reference Manual
are averaged to yield I
d1
. Using averaged current readings smooths out the noise.
d2
).
d1
).
d2
, and the current
d1
).
d1
).
d2
4200A-901-01 Rev. C / February 2017