-SCS Parameter Analyzer Reference Manual Section 2:
Connections and configuration
4200A-901-01 Rev. C / February 2017 2-19
Testing with less than ±20 V with SMUs
For testing discrete devices, you need a test fixture equipped with 3-lug triaxial connectors. This
allows the 4200A-SCS to be connected to the discrete device.
The next figure shows a basic test fixture to test a two-terminal device. For best performance when
testing with less than ±20 V, follow these standard industry practices:
• Use a metal test fixture
• Connect the metal fixture to COMMON
• Mount the DUT on high-resistivity terminals (for example, Teflon)
• Guarding will reduce leakage and parasite capacitance that degrades measurement quality
The Keithley Instruments Low Level Measurements Handbook provides an in-depth discussion on
guarding and other techniques that are useful for building quality test fixtures. See the Learning
Center on your 4200A-SCS for a copy.
Figure 24: Typical test fixture
The 4200A-SCS functions on all current ranges and up to ±20 V without the interlock being asserted.