Tektronix Keithley 4225-PMU - Page 108

Model 4200A
-SCS Pulse Card (PGU and PMU) User's Manual Section 4:
Pulse card concepts
4200A-PMU-900-01 Rev. B March 2023 4-19
Example 2: High resistance DUT
A high resistance DUT is shown in the following figure.
R
DUT
1 MΩ
Pulse V
high
5 V
Pulse V
low
0 V
Pulse load
50 Ω
Figure 89: 5 V pulse into a 1 MΩ DUT load
This example shows a 5 V pulse into a 1 MΩ DUT load.
Calculate the current, I
DUT
:
I
DUT
= V
TOTAL
/R
TOTAL
= V
INT
/ (50 Ω + 1 MΩ) = 10 V / 1.00005E+6 Ω = 9.9995E-6 A ≈ 10 µA.
Calculate V
DUT
:
V
DUT
= I
DUT
* R
DUT
= 10 µA * 1E6 Ω ≈ 10 V.
V
DUT
≈ 10 V because the pulse load = 50 Ω, but R
DUT
= 1 MΩ. The pulse generator calculates the
output voltage based on the pulse load, and uses a 2 times multiplier to determine V
INT
= 10 V. Since
the pulse generator cannot measure the output voltage or DUT load, this example results in a V
DUT
that is 2 times the programmed level.