Hi,
I'm working a design that has isolation between two sub-systems on one PCB (the grounds are separate). One side is a "high-speed" digital side with FPGAs and DDR doing DSP and the other side is an analog side that has high-resolution 24-bit ADCs and DACs.
I'm planning on using DC-balanced capacitive coupling to move data back and forth between the two sides. My concern is at happens when I AC-couple my signals across cross the split-grounds? Am I creating more noise due to the return/image current not having a continuous return plane? I have worked out both single-ended AC-coupling and schemes using LVDS/CML.
The capacitively coupled signals are