Hi,
I am designing a schematic of an open-loop transfer function for a buck dc-dc converter. I designed it with an opamp using an "E" voltage-controlled voltage source, a constant gain (to represent the pulse width modulator), and a low-pass filter based on the instructions in the assignment and need to do an AC sweep to get the magnitude and phase (Bode plot), but my schematic is NOT working. Someone PLEASE take a look and let me know what I'm doing wrong.

Thank you!!!

 

A Bode plot requires an input signal. You don't have one.