Keithley SourceMeter 2600 Series Reference Manual page 126

3-10 DUT Test Connections
Guarding and shielding
Source-measure performance and safety are optimized with the effective use of guarding
and shielding (noise and safety shields).
Guarding
A driven guard is always enabled and provides a buffered voltage that is at the
same level as the Input/Output HI voltage. The purpose of guarding is to eliminate
the effects of leakage current (and capacitance) that can exist between Input/
Output high and low. Without guarding, leakage and capacitance in the external
high-impedance test circuit could be high enough to adversely affect the
performance of the SourceMeter.
Guarding (shown in
condition:
•
Figure 3-9
High-impedance guarding
Noise shield
A noise shield (see
induced into the test circuit. Low level signals may benefit from effective shielding.
2600S-901-01 Rev. A / May 2006
Series 2600 System SourceMeters Reference Manual
Figure 3-9) should be used for the following source-measure
Test circuit impedance is >1GΩ
NOTE See "Guard" in
principles of guarding.
W
Figure 3-10) is used to prevent unwanted signals from being
Return to
Section 8
Section 3 topics
for details on the