Hi Xufei,
I see that you are looking for a way to see the channel's frequency response for the example "Architectural 112G PAM4 ADC-Based SerDes Model".
To analyze the frequency response of a channel in a Simulink model, you can use the "Linear Analysis" tool in Simulink. This tool is more appropriate for this purpose than the "frestimate" function, especially when dealing with complex models like the "Architectural 112G PAM4 ADC-Based SerDes Model".
In order to achieve your objective, open the Linear Analysis Tool, click on the "New Input-Output Transfer Response" button and select the input and output points. You can then compute the frequency response using the "Bode"button. The Bode plot is displayed in the Linear Analysis Tool.
The documentation for the Linear Analysis Tool can be found at: https://www.mathworks.com/help/control/linear-analysis.html
Hope this helps!
