The Designer's Guide Community Forum https://designers-guide.org/forum/YaBB.pl Measurements >> RF Measurements >> basic S-Parameter measurement https://designers-guide.org/forum/YaBB.pl?num=1227498618 Message started by reaman4ever on Nov 23rd, 2008, 7:50pm

Title: basic S-Parameter measurement Post by reaman4ever on Nov 23rd, 2008, 7:50pm Hello I apologize for the simple question, but I have been having trouble finding a detailed tutorial for this. I have a fully differential LNA that I am driving with a single source and an ideal_balun. The next stage is capacitive and not really resistive. To run an SP analysis, how many ports should I setup and where should I put them, and what settings do I have to put in them and in my SP analysis? If anyone has a detailed tutorial for a differential circuit like this, or can describe it here I would really really appreciate it. thank you very mcuh

Title: Re: basic S-Parameter measurement Post by pancho_hideboo on Nov 25th, 2008, 7:55pm reaman4ever wrote on Nov 23rd, 2008, 7:50pm: To run an SP analysis, how many ports should I setup and where should I put them, and what settings do I have to put in them and in my SP analysis? Consider actual measurement not EDA tool play. There four ports are connected to DUT. We don't use baluns. This is true for EDA tool play. If your network analyzer has only two ports, measure twice to get [S11,.....,S44]. If a simulator you are using has mixed-mode S-parameter analysis, activate mixed-mode S-parameter analysis. Or mixed-mode S-parameter calculation ability might be provided as post processing function in your simulator. Unfortunately if both are not true for your simulator, you have to calculate [Sdd, Sdc ; Scd, Scc] from [S11,.....,S44] by yourself. This is true for actual measurement using network analyzer. If your network analyzer is multiport type which have more than four ports, mixed mode S-parameters are calculated automatically. But if not, you have to calculate them from standard S-parameters. See http://cp.literature.agilent.com/litweb/pdf/5988-2923EN.pdf http://cp.literature.agilent.com/litweb/pdf/5988-9463EN.pdf http://na.tm.agilent.com/faq/TrueDiff_FAQ.pdf http://www.designers-guide.org/Analysis/diff-sp.pdf In EDA tool play, you can also evaluate [Sdd, Sdc ; Scd, Scc] using AC-analysis with common mode drive and differential drive without balun. Of course you can use ideal balun at input and output to evaluate [Sdd, Sdc ; Scd, Scc]. If you are understanding concept of mixed-mode S-parameters correctly, you can evaluate them by various methods in EDA tool.

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