I need to design a system on a four layer PCB. The layer stack-up from what I know would be
- signal / components
- ground plane
My problem is, I have a system with a power supply of +-5V and for one part of the system I need 3.3V analog and digital supply. What would be the best practice to realize the power distribution of this system?
My idea was to have one rail at the bottom of the power plane which is VSS and one rail at the top which is VDD and then have multiple fingers from the top to the bottom and vice versa similar to intra layer capacitors in chip design. For the 3.3V I'll just have a small area within the power plane dedicated for.
Would that make sense or is there a better solution for this kind of routing?
Edit: Here is a sketch of what I mean with multiple fingers from bottom and top of the power plane. This sketch displays my intended power plane. I hope this clarifies any misconceptions.
------------------------- | ______ ______ VDD = +5V | | __ | | __ | | | | | | | | | | | | | | | | | | | | | | |__| | | |__| | | |__| | | | | -----´ `-----´ `----- |_______________________ VSS = -5V