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Method to deemed S-parameter file (touchstone)

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Hawaslsh

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Hello,

I was given a four port s-parameter file for a SAW filter (SF2168E) from a company, RFMi, and I was told the file was of a demo board which included tuning elements. Is there a method to deemed the tuning elements to work with the S-parameters of the device itself? Below is a picture of the schematic of their demo board.

figure1.PNG

Would it really be as simple as using negative value components as depicted below?
1652406292151.png

I did a few tests with ideal components and a known s-parameter file and it seemed to work, but I wanted to make sure I wasn't missing something obvious.
Thanks,
Sami
 

No, you have to de-embed the components but what you're gonna do s-parameters of the SAW filter itself ? It has only one application and the company has already designed the matching circuit.
Note: Your app. circuit is wrong. The Inductances should be placed first.
 

what you're gonna do s-parameters of the SAW filter itself?
The network they suggest is for a differential input. The company says the part can be used single ended, so I want to make a matching network when pins 2 and 5 are tried directly to ground and avoid having to place the 6 extra components in their initially designed network.

Note: Your app. circuit is wrong. The Inductances should be placed first.
Perhaps I am not interpreting what you said here. The 4 port block in the center of the bottom pictire contains the entire circuit from the top picture. i reversed the order of the negative valued parts in the bottom picture (the negative sign turned out very poorly in the picture). I wanted to put the -10nH inductor in parallel with the +10nH imbedded in the SParameter file so their reactances would cancel. I suppose it’s not completely representative since the real inductor on their demo board has some resistance.
--- Updated ---

what you're gonna do s-parameters of the SAW filter itself?
The network they suggest is for a differential input. The company says the part can be used single ended, so I want to make a matching network when pins 2 and 5 are tried directly to ground and avoid having to place the 6 extra components in their initially designed network.

Note: Your app. circuit is wrong. The Inductances should be placed first.
Perhaps I am not interpreting what you said here. The 4 port block in the center of the bottom pictire contains the entire circuit from the top picture. i reversed the order of the negative valued parts in the bottom picture (the negative sign turned out very poorly in the picture). I wanted to put the -10nH inductor in parallel with the +10nH imbedded in the SParameter file so their reactances would cancel. I suppose it’s not completely representative since the real inductor on their demo board has some resistance.
 

The most practical method is to measure this SAW filter on a test bed. De-Embedding may not give you very accurate result.
Place 2 Balun transformers at both sides then measure.
 

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