Rohde & Schwarz R&S ZNA Series - 4.6.2.2 Deembedding a DUT; 4.6.2.3 Circuit models for 2-port networks

Concepts and features
R&S
®
ZNA
235User Manual 1178.6462.02 ─ 29
This method provides a number of advantages:
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The measurement uncertainty is not impaired by the tolerances of real test fixtures.
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There is no need to fabricate test fixtures with integrated matching circuits for each
type of DUT.
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Calibration can be performed at the DUT's ports. If necessary, (e.g. for compensat-
ing for the effect of a test fixture) it is possible to shift the calibration plane using
length offset parameters.
4.6.2.2 Deembedding a DUT
Deembedding and embedding are inverse operations: A deembedding problem is
given if an arbitrary real network connected to the DUT is to be virtually removed to
obtain the characteristics of the DUT alone. Deembedding is typically used for DUTs
which are not directly accessible because they are inseparably connected to other
components, e.g. for MMICs in a package or connectors soldered to an adapter board.
To be numerically removed, the real network must be described by a set of S-parame-
ters or by an equivalent circuit of lumped elements. Deembedding the DUT effectively
extends the calibration plane towards the DUT ports, enabling a realistic evaluation of
the DUT without the distorting network. Deembedding can be combined with length off-
set parameters; see Chapter 4.6.1, "Offset parameters", on page 228.
The simplest case of single port deembedding can be depicted as follows:
4.6.2.3 Circuit models for 2-port networks
The lumped element 2-port transformation networks for (de-)embedding consist of the
following two basic circuit blocks:
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a capacitor connected in parallel with a resistor
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an inductor connected in series with a resistor
The 2-port transformation networks comprise all possible combinations of 2 basic
blocks, where either one block represents a serial and the other a shunt element or
both represent shunt elements. In the default setting the resistors are not effective,
since the serial resistances are set to 0 Ω, the shunt resistances are set to 10 MΩ and
the shunt inductances are set to 0 Siemens.
Offset parameters and de-/embedding