Hi All, quick simple question to those who knows with possible follow up, here is a little crude(abstract) diagram below but hopefully it should work to explain the question:
For example I have 2(or more) layers PCB with a hole in the middle (rectangular cutout in the middle), one of the layers in the PCB is designated for GND, just once ground plane for everything and all GND pins from all the devices in the system are going to that plane through vias.
This is very fundamental circuit but I am trying to understand the flow of the current in this system so that later I can better design mixed system with analog and digital grounds separate etc...
Anyways, in the attached picture the way this works is that I have a power source (i.e. the battery) at the top/right corner of the board, then I have a switching regulator at the low/right corner that power from the battery (using path A as it seems to be the shortest way to power source) and converting it to desires value and then sends it to the microprocessor in the top/left corner (path B).
My question is: will the return current for the microprocessor be along path "B" or along Path "C"? I have a mental clog about this simple thing and no one to ask around, since microprocessor takes power from voltage regulator's output capacitors then maybe it will probably be the return path as well, or since I dump ground pins directly to the ground plane maybe then return path will be directly into the battery since it seems to the the shortest way between microprocessor and battery?
Can someone help please?