fit S11to poles and zeros like in the article

Hello,In the article bellow they refer to a method of converting s1p file (attached as text into a pole zero model .

could you please show me how can i convert the S1P file into such model using matlab?

Thanks.

https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9790659&tag=1

Answer 1

[Anudeep Kumar]

Hey @fima v

I believe you can use various MATLAB functions as 'sparameters','rationalfit' based on your data to achieve your goal.

You can extract your Touchstone S-Parameter file using 'sparameters' as below

% Read the S1P file
sobj = sparameters('model_txt.txt'); % It is preferred the file is in .s1p or compatible format.
freq = sobj.Frequencies;      % Frequency vector (Hz)
s11 = rfparam(sobj,1,1);      % S11 parameter (complex)

Then depending on your corcuit you may need to convert S11 to impedance or admittance.

Using 'rationalfit' you can fit a rational fucntion to your data to get Poles and Zeros. Then based on the formula metioned in the attached article you can write a simple code to calculate 'Ms1' and 'M11' with your extracted Zeros and Poles.

I have hereby attached the documentations of the functions mentioned for your reference:

https://www.mathworks.com/help/releases/R2024b/rf/ref/sparameters.html

https://www.mathworks.com/help/releases/R2024b/rf/ref/rationalfit.html

I have also attached some examples and tutorials provided by MATLAB on this topic which might be relevant and help you achieve your goal.

https://www.mathworks.com/discovery/s-parameter.html

I hope this helps to some extent!