Ratio and Delta 5-21
Figure 5-7
H-V Curve (Fixed I)
Delta measurements — As previously explained, the DC current reversal measurement
technique must be used to cancel the effects of thermal EMFs in the test leads. By configuring
a custom sweep, the SourceMeter can function as a bipolar, fixed amplitude source. For
example, if the test requires a fixed current of 1mA, the custom sweep can be configured to
alternate between +1mA and -1mA (see Figure 5-8). By enabling Delta measurements on the
Model 2182, the effects of thermal EMFs in the test leads will automatically be canceled during
the source-measure process.
Figure 5-8
SourceMeter output—2-point custom sweep
The procedure to use the SourceMeter and Model 2182 to perform Delta measurements is
provided in “Delta measurement procedure using a SourceMeter.” That procedure (presented
earlier in this section under “Delta”) uses a 2-point custom sweep, which is required for this
application.
Measure
V
Fixed I
Magnetic Field (H)
P0
P1
P0
P1
...
0
+1mA
–1mA
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