I'm designing a PCB with 4 layers, but I've seen different recommendations about layer distribution. I'm considering that:
Top layer - Signal + short traces of VCC
2nd layer - Signal
3rd layer - VCC
4th layer - GND
Can I fill all area around with ground in each plane and place several vias to connect grounds across the layers? Can I have the VCC layer filled with ground plane?
The circuit has a nordic + lora radio in one module castellation. Output antenna has a connector over the module already, so no need to design microstrip lines.
What is the minimum recommended power trace width for a 3.3 V and 150 mA maximum? Shall I have very large traces in 3rd layer and not filled with ground around?