Deembedding (Option R&S RTP-K121/-K122)
R&S
®
RTP
1061User Manual 1337.9952.02 ─ 12
19 Deembedding (Option R&S RTP-K121/-
K122)
Deembedding removes the parasitic effects of the measurement setup from the mea-
sured signal. A simple measurement setup consists of a probe only, but more complex
setups include also cables, fixtures and other components. The effects of these com-
ponents on the measurement are typically increasing when signal frequency increases.
Thus, deembedding is useful or even necessary when measuring signals of 4 GHz fre-
quency or higher. Furthermore, you can virtually move the measurement point to a
point in a circuit that cannot be reached by probing. In this case, the effects of the com-
ponents between the real and ideal probe are deembedded.
The components of a measurement setup are usually multiports, and each multiport
can be described by a scattering matrix. The elements of a scattering matrix are the S-
parameters. The S-parameters of a multiport are usually measured using vector net-
work analyzers (VNA), and they are saved in Touchstone files.
The R&S RTP also can measure probes and cables and determine their S-parameters.
These components are called proven probe or proven cable, and their characteristics
are saved in *.rs2p files. The measurements require hardware option R&S RTP-B7.
For proven probe, also the R&S RT-ZF30 probe test fixture is needed
From the S-parameters of the measurement components, the deembedding option
determines the transfer function for the measurement setup. Based on the transfer
function, filter coefficients are calculated, and the filter is applied to the measured sig-
nal.
Option R&S RTP-K121 realizes the deembedding process in software. As the process
requires some time, triggering on the corrected signal is not possible, and the acquisi-
tion rate decreases.
Option R&S RTP-K122 realizes the deembedding process in hardware. This process is
fast, so you can trigger on the corrected signal, and the acquisition rate remains
unchanged. However, deembedding by hardware is typically less precise but the accu-
racy is sufficient for most measurements.
19.1 Configuring the measurement setup for deembedding
The R&S RTP provides an easy way to model the measurement setup on the instru-
ment, and to enter the characteristics of the components. If you use an R&S RT-ZM,
R&S RT-ZD or R&S RT-ZS probe with Rohde & Schwarz interface, the setup is easy:
The probe is recognized by the oscilloscope, and the oscilloscope knows the charac-
teristics of the probe components.
Before you start, you need to know the following:
●
Probing method: probing or terminating
●
S-parameter files of the components of the measurement setup (Touchstone files).
Configuring the measurement setup for deembedding
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