Anritsu 37 C Series, Руководство по эксплуатации, Страница: 186 / 603

In some cases—depending on the fixture or the device being meas-
ured—this is satisfactory. But when it is not, we need to employ other
techniques.
One of the reasons that moving the reference plane out to the device
does not always work, is that the test fixture includes a transition
from coax to a structure such as microstrip, coplanar waveguide, or
stripline (Figure 8-23).
Engineers have come to grips with the general problem. However,
there is no established standard approach. Two of the more common
approaches are to calibrate the fixture as a part of the analyzer, and to
characterize the fixture and compute the desired result.
ACTIVE DEVICE MEASUREMENTS
8-26 37XXXC OM
G P C - 7 D U T
5 0 O H M L I N E
N O L O S S , R E F L E C T I O N L E S S
Figure 8-22. Simple Example of De-Embedding
WHAT DO WE DO?
TWO APPROACHES ARE COMMON
Calibrate the Fixture As
“Part of the Analyzer”
Characterize the Fixture and Com-
pute the Desired Result
G R O U N D
I N P U T
F E T
C O P L A N A R
L A U N C H E R
I N P U T
G R O U N D
G R O U N D G R O U N D
C O P L A N A R
L A U N C H E R
A L U M I N A
C A R R I E R
Figure 8-23. Coax-to-Substrate Transition