I have noticed, in my opinion, some misconceptions in the layout of the majority of DC to DC step-down converters.
I've seen in many PCBs that the trace that goes to the input of the converter (point A) and the trace that goes from the output to the power inductor (point B) are usually too thick. In my opinion it doesn't have to be thicker or same thick as the trace of the output of the power inductor (point C - LC circuit).
The voltage at point A and point B in respect to ground are (usually) the same, so the current is much lower than the output at the trace C.
So, why do many engineers use thicker trace for those nets? Am I missing something?
Moreover, in many PCBs especially high density boards the power components may be seperated in both sides which I think they should be on the same side. And the input loop should share the same ground path with the output loop. Is that correct?