I understand that you are facing an error with the step size during simulation of a model containing N-channel parameterized MOSFET blocks in Simulink.
It is difficult to provide you a specific answer without investigating the actual model, but one of the instances when this error can occur is when the solver is unable to solve the system/model within the step-size provided.
One of the recommended ways to resolve this error is to increase the number of consecutive minimum steps the model is taking. This value can be modified by expanding the "Additional options" section in "Solver Section" of the "Configuration Parameters" menu.
In this section, you should see a dialog box with the title "Number of consecutive min steps:" next to it. You can try to increase the value in this box.
You can also try to relax all the tolerances in the model from the model's "Configuration Parameters".
Alternatively, if this does not fix the issue, you can also try changing the solver being used, possibly to ode23t (if not using it already).
Hope this helps!
