facturer may specify the current value, it is often desirable to
verify the specification for a particular sample of the device.
Then too, the specified leakage current might be at a higher
voltage than required. For example, the specified leakage cur-
rent might be 11~4 with an applied voltage of 25V, while that
figure might be much less at an operating value of 1OV.
An added bonus of using the Model 617 in this situation is
that the instrument has a built in voltage source. Thus, the
voltage source could be programmed to the desired value or
values, and the leakage current could be measured for each
voltage. In this manner, leakage current characterization
studies could be perfomed with only a single measuring in-
strument, rather than requiring a separate voltage source.
As shown in Figure 4-5, a shielded test fixture such as the
Keithley Model 6104 should be used to keep the measurement
quiet and stable. A good quality low-noise cable, such as the
Model 4801 connected through a Model 6147 adapter should
be used to connect the current input to the instnnnent.
Forward and reverse diode currents could be measured in a
similar manner. The forward leakage current (measured with
‘--Il.::
V-SOURCE OUTPUT
0
LO HI
0
MODEL 6147 TRIAX
TO BNC ADAPTER
\ II
MODEL 4801 CABLE
r----
---
1
\
\ \
617 SET TO AMPS
/
\
TEST FIXTURE
\
POMONA MODEL 4686 PATCH CORDS
617 PREAMP
6104 SHIELD
------
r-l
-~~~~~~~--AID
>LO
1.
- V-SOURCE
-+>H’
T
Figure 4-5. Leakage Current Measurement
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