We understand you are new. So here is some help.
You said FET, so I drew one and the circuit does make some sense.
but
The TIP120 part is most definitely not an FET.
The TIP120 is an NPN Epitaxial Darlington Transistor and therefore needs (not optional) at least a 1000 ohm transistor between the PWM pin and the BASE pin.
In other words, this is what you need.
