Concepts and Features
R&S
®
ZNB/ZNBT
182
User Manual 1173.9163.02 ─ 38
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Transformation networks can be defined by a set of S-parameters stored in a
Touchstone file or by an equivalent circuit with lumped elements.
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The same networks are available for embedding and deembedding.
4.6.2.1
Embedding a DUT
To be integrated in application circuits, high-impedance components like Surface
Acoustic Wave (SAW) filters are often combined with a matching network. To obtain
the characteristics of a component with an added matching network, both must be inte-
grated in the measurement circuit of the network analyzer.
The figure below shows a DUT with a single-ended and a balanced port that is com-
bined with a real matching circuit and a physical unbalance-balance transformer
(balun) in order to be evaluated in a 2-port measurement.
The idea of virtual embedding is to simulate the matching network and avoid using
physical circuitry so that the analyzer ports can be directly connected to the input and
output ports of the DUT. The matching circuit is taken into account numerically. The
analyzer measures the DUT alone but provides the characteristics of the DUT, includ-
ing the desired matching circuit.
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.
Offset Parameters and Embedding
