![Tektronix Keithley 4200-SMU Скачать руководство пользователя страница 119](http://html1.mh-extra.com/html/tektronix/keithley-4200-smu/keithley-4200-smu_user-manual_1078017119.webp)
Section 6: Optimizing SMU measurements
Model 4200A-SCS Source-Measure Unit (SMU) User's Manual
6-12
4200A-SMU-900-01 Rev. A December 2020
Ground loops and other SMU grounding considerations
Ground loops, which occur when more than one point in a test system is connected to safety (earth)
ground, can create error signals that cause erratic or erroneous performance. The configuration
shown in the following figure shows a ground loop that is created by connecting 4200A-SCS signal
COMMON and DUT LO to safety (earth) ground. A large ground current flowing in the loop will
encounter small resistances, either in the conductors or at the connecting points. This small
resistance results in voltage drops that can affect performance.
To prevent ground loops, connect the test system to ground at a single point. If it is not possible to
remove the DUT ground, remove the ground link between the GNDU COMMON terminal and chassis
ground, as shown in the following figure.
Removing the COMMON-to-chassis link may result in oscillations (refer to
(on page 6-1)).
Figure 102: Ground loops
Figure 103: Eliminating ground loops