Keithley 4200A-SCS Reference Manual

Section
8: Keithley User Library Tool (KULT) Model 4200A-SCS Parameter Analyzer
Reference Manual
8-40 4200A-901-01 Rev. C / February 2017
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
g
) to saturate the MOSFET.
2. Applies 3 V to the drain (V
d1
) and performs a current measurement (I
d1
).
3. Applies 5 V to the drain (V
d2
) and performs another current measurement (I
d2
).
Calculates the drain-to-source resistance rdson as follows:
rdson = (V
d2
-V
d1
) / (I
d2
-I
d1
)
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
d1
and ten more at V
d2
. The current readings at V
d1
are averaged to yield I
d1
, and the current
readings at V
d2
are averaged to yield I
d2
. Using averaged current readings smooths out the noise.
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
g
) to saturate the MOSFET.
2. Applies 3 V to the drain (V
d1
) and makes ten current measurements.
3. Averages the 10 current readings to yield a single reading (I
d1
).
4. Applies 5 V to the drain (V
d2
) and makes ten more current measurements.
5. Averages the ten current readings to yield a single reading (I
d2
).
6. Calculates the drain-to-source resistance (rdsonAvg) as follows:
rdsonAvg = (V
d2
-V
d1
) / (I
d2
-I
d1
)

Keithley 4200A-SCS Specifications

General

Brand	Keithley
Model	4200A-SCS
Category	Measuring Instruments
Language	English