I am designing a system that incorporates an FPGA, a few ADCs, and a few DACs. I am curious as to what my best options may be for grounding in my system.
The FPGA is on its own daughter board, but digital signals coming from it could be up to 25MHz. The ADCs will be clocked by this 25MHz signal. The signals going to the DACs will not be any faster than 5MHz. The DACs themselves are connected to a chain of op-amps, which are being used to generate a high-voltage (between 65V and -65V) DC signal. This DC signal will not change any faster than 500kHz.
From the research I've done, it seems that there's no One Good Way™ to connect analog and digital grounds in a sensitive circuit. That being said, I'm hoping someone with more experience than me can weigh in on what grounding technique may be the most effective for my application. Initially in my schematic, I separated analog and digital grounds and planned to follow a "fenced" design, where a long slot would separate the analog and digital ground, and they would only be connected in a few places. Some of the analog components share power rails with each other, but none of them share a power supply with the digital components.
Based on the types of signals and frequencies I'm operating at, is what I'm thinking considered overkill? Not enough? Any advice is appreciated.