Keysight B1505A Configuration and Connection Guide
5-51
Connection Guide for Wafer Prober and Your Own Test Fixture
About Cable Connections
To Make Connection to Reduce Leakage Current
To reduce the leakage current caused by connection cables, the guard technique is
effective. Connect the probing needles to the coaxial cables as shown below:
1. Cut and trim end of the coaxial cable such as N1254A-503 and N1254A-506, so that
the center conductor does not touch the outer conductor (connected to the guard
terminal).
2. Connect the center conductor to tail of the probing needle. Never connect the outer
conductor to the probing needle. However the outer conductor should be extended as
close as possible to the probing needle.
3. Connect the outer conductor to the outer conductor of the probing needle if it is a
coaxial probing needle.
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.
WARNING
Do not touch the guard terminal with bare hands because you may be shocked by
high voltage. The potential of the guard terminal is equal to the output voltage.
CAUTION
Never connect the guard terminal to any other output, including circuit common, frame
ground, or the terminals of any other unit.
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.
Probing needle
Contact pad
Outer conductor
Center conductor
Coaxial cable
A
Buffer
Guard
Force
DUT
Summary of Contents for B1505A
Page 3: ......
Page 9: ...1 Configuration Guide ...
Page 83: ...2 N1259A Connection Guide ...
Page 107: ...3 N1265A Connection Guide ...
Page 133: ...4 N1272A and N1273A Connection Guide ...
Page 149: ...5 Connection Guide for Wafer Prober and Your Own Test Fixture ...
Page 203: ...6 Accessory Dimensions ...
Page 219: ...7 Connection and Ordering Examples ...
Page 297: ......