FEDEVEL
Platform forum

Fallingelectron , 06-07-2025, 03:24 PM

I have to do a polygon fill of supply rails, its a bi polar supply with +70V 0V -70V how should i do it on a 4 layer pcb, its for a class D amplifier and the power supply input section is on 1 quadrant of the pcb please guide me

QDrives , 06-08-2025, 02:41 AM

"**have to**"?
There is often no need to use power layers. At least, not for something slow like a class D amplifier.
On L2 you have the reference for the signal(s) on L1.

Fallingelectron , 06-08-2025, 06:47 AM

Yes there won’t be a plain but copper polygons as there will be a current draw of 16 to 20 amps

QDrives , 06-08-2025, 09:09 PM

Plane, not plain. Pronounced the same, but different meaning. But that is beside the point.

If L2 has the reference for L1, then L3 will have the reference for L4.
How to route, is about following the current path. The return is in the reference 'plane'.
One other tip: decoupling capacitors are named that because they decouple the more DC part of the power supply from the high(er) switching speed on other parts. Although for 20A you may need some big aluminium ones.