Anritsu 37 C Series, Operation Manual

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It is also possible to use three known impedances. For instance, a var-
actor with three voltages applied (Figure 8-26).
The second approach is to model the fixture. Modeling is elegant but of
limited use due to the non-ideal characteristics of the fixture. Model-
ing can be accomplished in a CAD system like Touchstone or Compass.
In summary, there are quite a variety of approaches—all with their
own characteristic pitfalls. Engineers try to choose the most appropri-
ate technique for their application.
ACTIVE DEVICE MEASUREMENTS
8-28 37XXXC OM
C 1
C 2
C 3
C I S V A R I E D
B Y C H A N G I N G
V O L T A G E
N O T P E R F E C T E I T H E R
S P E C I A L C A L I B R A T I O N K I T S
Figure 8-26. Three Known Impedances
APPROACH NUMBER 2
CHARACTERIZE THE FIXTURE
Model
Measure
Compute the Desired Result
You should turn off or disconnect the bias supplies during the calibra-
tion, since you are using a Short as the calibration standard.
CAUTION