To generate Successive Approximation Register(SAR) ADC signal, you can use the “SAR ADC” block available in Simulink. I am assuming that you are using MATLAB version of R2019a or higher.
- Double click on Simulink Canvas and search for “SAR ADC” available in “Mixed-Signal Blockset / ADC / Architectures” Library.
- You can refer to the below MathWorks documentation link to know more about “SAR ADC” block: https://www.mathworks.com/help/msblks/ref/saradc.html#mw_0f726858-ae5d-49c0-b8a4-226533fa0b6b_vh
Hope these references will get you started.