I'm seeing strange voltage at the switch node of my buck regulator.
There is a decaying sine wave of voltage which seems to happen before the switch is enabled. This is a dual channel regulator and I'm only seeing it on channel 1, the switching waveform for channel 2 is nice and square, so I'm expecting it to be an error in the pcb assembly (done by me, with low skill level). But I can't find anything wrong/missing. Any pointers on where to focus investigation would be most welcome.
Note the bottom side FET is not supported by diode (D3), this is not fitted (in either channel).