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12.3 De-Embedding of the Multiplexer
As the calibration of the multiplexer unit according to section 12.2 is quite
labor-intensive, the de-embedding functionality (see chapter 8 ) can be used
as an alternative to minimize the errors caused by the multiplexer.
The advantage is, that only the TDR system needs to be calibrated while the
multiplexer influence is de-embedded. The basic requirement for this is the
availability of the S-parameters for all signal paths of the multiplexer. In this
scenario the calibration takes place in the plane CH 1 / CH 2 right before the
multiplexer (see Fig. 18 ). The work flow to de-embed the multiplexer is as
follows:
1. Make sure the S-parameters for all multiplexer channels are available
as Touchstone
s2p
files.
Remark: If the parameters are unavailable, it is possible to create them as
described in section 8.3 .
2. Perform the TTC/12TC-calibration according to chapter 5 at the end
of the cables to be connected to the multiplexer. At the end of the
wizard, the user is informed that the calibration just performed is now
applied to all channels, as described in section 12.2 , no. 3.a.
3. Connect the TDR to the multiplexer via coaxial cable(s).
4. Open the De-Embedding Dialog via the tool button in the Main
Window and select all corresponding Touchstone files for the individ-
ual channels.
5. Close the dialog with OK and save your work to a
mas
Project File . The
de-embedding tool button should have turned green meanwhile.
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