Agilent Technologies E5070B, User Manual

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Chapter 7 307
Fixture Simulator
Example of Using Fixture Simulator
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Figure 7-21 DUT evaluation using an actual test fixture
Problems in measurement with an actual test fixture
Evaluating a balanced device with an actual test fixture involves the following problems:
• Calibration cannot be performed at the DUT’s terminals. (A DUT’s terminals are in the
test fixture and calibration standards cannot be connected to them. In addition, it is very
difficult to obtain calibration standards that can be used to calibrate a balanced port.)
As a result, calibration is performed at appropriate connectors connected to the test
fixture, and the network between the calibration reference plane and the DUT’s
terminals induces measurement errors.
• Different test fixtures must be fabricated for evaluating different types of DUTs
because they require different characteristic impedances and matching circuits.
• An actual balun does not have ideal characteristics, so measurement error cannot be
avoided. Furthermore, a common mode signal evaluation cannot be performed when an
actual balun is used.