AD9361 differential input impedance for RX ports

The differential impedance of AD9361 is expected to be close to 100 Ohm. However, extracting it from the S-parameter s1p and s2p files, provided here, results in 43.14-j63.77 Ohm. RF simulations confirmed this low value. Could you please advise about this issue?

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    •  Analog Employees 
    on Oct 8, 2019 11:29 AM

    Rx input impedance varies significantly over frequency. 

    For spot frequency impedance refer to the S-Parameter file.

  • Thank you. I understood that it is not an easy question. The problem is in the S-parameter files. There are at least two drawbacks: too many measurement points and simulation software cannot work with these files, and the second is the problem with Touchstone formatting. Probably with return signs at the end of the line. And due to the enormous quantity of points, it is hard to fix. The only way is to manually extract the numbers from the S-parameter file for the single frequency of interest and then calculate the differential impedance. Or devote a lot of time to write a code that does it automatically. I did not expect from so reputable company as Analog Device is so reckless actions in regards to the supplied S-parameter files.

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  • Thank you. I understood that it is not an easy question. The problem is in the S-parameter files. There are at least two drawbacks: too many measurement points and simulation software cannot work with these files, and the second is the problem with Touchstone formatting. Probably with return signs at the end of the line. And due to the enormous quantity of points, it is hard to fix. The only way is to manually extract the numbers from the S-parameter file for the single frequency of interest and then calculate the differential impedance. Or devote a lot of time to write a code that does it automatically. I did not expect from so reputable company as Analog Device is so reckless actions in regards to the supplied S-parameter files.

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