John,
I would consider two things first:
1. When you find square root of the matrix using your formula (T_2p5inch
*T_2p5inch = T_5inch ==> T_2p5inch=T_5inch^ 0.5), how do you ensure phase
discontinuity? As we know any complex number has two distinct roots, how do you
choose the right ones as eigenvalues of the new matrix? The proper way would be
to start from low frequency, increment it and what for continuous change of the
phase of each eigenvalue in proper direction.
2. T-lines sometime could not be the only thing on the sides. Can you factor
out the probes, e.g. SMA connectors, each one having geometrically mirrored
model?
Vladimir
-----Original Message-----
From: FreeLists Mailing List Manager [mailto:ecartis@xxxxxxxxxxxxx] ;
Sent: Sunday, May 22, 2016 11:08 PM
To: si-list digest users
Subject: si-list Digest V16 #132
si-list Digest Mon, 23 May 2016 Volume: 16 Issue: 132
In This Issue:
#1: From: John Lin <johnlinc@xxxxxxxxx>
Subject: [SI-LIST] De-embedding issue.
----------------------------------------------------------------------
Msg: #1 in digest
Date: Mon, 23 May 2016 12:00:31 +0800
Subject: [SI-LIST] De-embedding issue.
From: John Lin <johnlinc@xxxxxxxxx>
Dear all SI gurus,
While doing de-embedding by removing 5 inch trace as fixture from 16 inch
trace, I find there are many spikes on my de-embedded S21 plot.
Here are my approaches.
1. Transfer both 5 inch and 16 inch S2P file to T paramter (matrix) 2. cut the
5inch into half by T_2p5inch *T_2p5inch = T_5inch ==> T_2p5inch=T_5inch^
0.5; assuming symmetry.
3. do inverse(T_2p5inch)
4. De-embedded result = inv(T_2p5inch)*T_16inch*inv(T_2p5inch)
5. Convert De-embedded T parameters back to S parameters.
I also use Delta-L for de-embedding. Both S21 plot can match well, except
the spikes.
I don't know what happen for the spikes and seek any idea from you.
Thanks,
John Lin
------------------------------
End of si-list Digest V16 #132
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