![background image](http://html2.mh-extra.com/html/keithley/sourcemeter-2601/sourcemeter-2601_reference-manual_4018913116.webp)
3-12
Return to
2600S-901-01 Rev. C / January 2008
Section 3: DUT Test Connections
Series 2600 System SourceMeter® Instruments Reference Manual
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
) should be used for the following source-measure condition:
• Test circuit impedance is >1G
Ω.
in Section 8 for details on the principles
of guarding.
Figure 3-10
CHANNEL A
LO
G
LO
HI G G G HI
S
S
KEITHLEY Series 2600
DUT
HI
LO
Metal Guard
Shield
Guard Shield
The guard shield can be the shield of a
coaxial cable, or it can be an insulated
foil that surrounds the conductor.
>1G
W
Models 2602 and 2612 high-impedance guarding