How to use curve fitting to get transfer function in frequency domain?

Hi all,

I have the data of sweep frequency scan of my circuit, both magnitude and phase. I am trying to use matlab curve fitting to obtain a transfer function from it. Can someone give help on this? Since I don't see curve fitting tool can import both magnitude and phase data in one fitting.

Answer 1

[Zack Peters]

Hi Siyu,

Rather than go through the Curve Fitting toolbox, I recommend one of two other avenues.

1. Go directly to a linearized model (TF or SS representation) via Simulink Control Design toolbox. You can linearize model around a particular operating point or set of operating points.
2. If you want to get a frequency sweep and then convert to transfer function. I would recommend get a frequency response estimate through our Simulink Control Design toolbox and then pass that data into the System Identification toolbox to get an estimated model of your system

~Zack

[Siyu He]

Hi Zack, Thanks for your reply.The data I have comes from my circuit,so I want to get estimated TF. I'll try control design tool box and let you know what I get.

He,siyu

[Siyu He]

Hi, Zack. I was busy with my tests and did not have time to try simulink. which block should I use to convert my frequency response data to transfer function? Should I choose one from System Identification Toolbox not from Simulink Control Design?

Answer 2

[Siyu He]

Hi, which block should I use to convert my frequency response data to transfer function? Should I choose one from System Identification Toolbox not from Simulink Control Design?