User`s guide

10-6 Agilent 4155C/4156C User’s Guide Vol.2, Edition 6
Connecting Measurement Devices
Using Connector Plate
Example
The following example connection can be used to reduce the leakage current.
Extend the outer conductor as close as possible to the probing needle. This also
reduces the induced noise.
Guarding
Guarding reduces the leakage current between the measurement points and
instrument. This is important when you measure low current.
The following figure shows the theory of guarding. The buffer amplifier (×1) keeps
the potential of the guard conductor at the same potential as the force conductor, so
current does not flow between the force and guard conductors. Therefore, the
current measured by SMU is same as current at measurement point because no
current is leaked.