4-Port Scatter parameters to 2-Port Scatter Paremeters

Is it always customary to convert 4-Port S-Parameters to 2-Port S-Parameters and then plot Smith's chart ? Why ?

Answer 1

[Giorgia Zucchelli]

Dear Jay,

Converting S-parameters can be done, but it is not compulsory. I can imagine that you might want to do it when you are interested only in a pair of ports (e.g. selecting a certain channel in multi-port measurements, and terminate all the other ports with a certain impedance), or if you want to translate single ended measurements to differential data. Plotting on a smith chart is then done to visualize the input or the output port behaviour.

With best regards,

Giorgia

[analogy]

Okay, by the way, do you have any good documentation that explains 4-Port single ended conversion to 2-Port differential (apart from MATLAB documentation) or as a matter of fact, any documentation explain the process of single ended scattering parameter conversion to differential ended scattering parameter ?

Answer 2

[Giorgia Zucchelli]

Hi,

The RF Toolbox documetation references this article "Mixed-Mode S-Parameter Characterization of Differential Structures" by Fan, W., A. C. W. Lu, L. L. Wai, and B. K. Lok, published on Electronic Packaging Technology Conference, pp. 533–537, 2003.

I think that this is a good starting point to discuss the differences and the derivation between the two.

With best regards,

Giorgia