Keithley 4200A-SCS - Page 64

Model 4200A
-SCS Parameter Analyzer Reference Manual Section 3: Source-
measure hardware
4200A-901-01 Rev. C / February 2017 3-9
As shown in the following figure, the load line for 20 kΩ intersects the 50 V voltage source line at
2.5 mA.
Figure 39: Normal voltage source operation
The next figure shows what happens if the resistance of the load is decreased to 8 kΩ. The DUT load
line for 8 kΩ intersects the current compliance limit line, which places the SMU in compliance. In
compliance, the SMU cannot source its programmed voltage (50 V). For the 8 kΩ DUT, the SMU will
only output 40 V (at the 5 mA limit).
Notice that as resistance decreases, the slope of the DUT load line increases. As resistance
approaches infinity (open output), the SMU will source about 50 V at 0 mA. However, as resistance
decreases, the slope of the DUT load line increases. At zero resistance (shorted output), the SMU will
source virtually 0 V at 5 mA.
Regardless of the load, current never exceeds the programmed compliance of 5 mA.
Figure 40: Voltage source in compliance