Section 3: Working with devices and instruments
Model 8010 High Power Device Test Fixture User's Manual
3-14
8010-900-01 Rev. C / March 2017
The next figures show how a cable guard can eliminate leakage current through the insulators in a
test fixture. In these figures, leakage current (I
L
) flows through the insulators (R
L1
and R
L2
) to LO,
adversely affecting the DUT low-current (or high-resistance) measurement.
Also, in the next figures, the driven guard is connected to the cable shield and extended to the metal
guard plate for the insulators. Since the voltage on either end of R
L1
is the same (0 V
drop
), no current
will flow through the leakage resistance path. Therefore, the SourceMeter instrument only measures
the current through the DUT.
Note that the Model 8010 is a safety shield.
Figure 20: Model 8010 unguarded measurements
Figure 21: Model 8010 guarded measurements