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Model 4277A
SECTION III
where E bias is the bias voltage (V)
applied to EXT INPUT/INT MONITOR
connector and Rx is the dc resistance
(kfi) of the sample.
9. Read the measured values.
10. Gradually decrease the de voltage source
output voltage until the dc bias current is
0mA, then remove the sample from the
test fixture or test leads.
Note
To make stable measurements, connect
an
ac
bypass
capacitor
(near
1 pF)
between the positive terminal and the
negative terminal of the dc voltage
source.
Note
Maximum allowable current depends on
the bridge circuit's range resistor, as
listed in the table below.
Range Resistor
Maximum Output Current
lOOU
35mA
lkS2 and
lom
10mA
Refer to Figure 3-5 for details on the
relation
between
range
resistor and
measurement
range.
Note
that
measurement accuracies, as specified
in Section I, are not guaranteed if bias
current is allowed to exceed the limits
given in the above table.
Figure 3-23. External DC Bias (Sheet 4 of 4),
3-53
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