robertferanec , 08-28-2018, 02:53 AM
1. There is no universal rule for all boards and designs. Maybe in your case you need to split the grounds
2. I read some documents about grounds, but you will find everything what you are looking for - e.g. you can find documents what will be telling you separate the grounds and you will also find documents what will be telling you to use a solid GND.
When I was not sure, I separated the grounds, but I placed number of 0R footprints around the separation, so during the EMC/EMI/ESD and noise testing I could try different situations (I would only leave one 0R fitted to connect AGND with GND together or I would fit all the 0R to connect the GND and AGND in multiple places trying to emulate solid GND connection). Using 0R resistors is not as good as solid GND, but you will at least get and idea what could be better - if separated GND or solid GND.