How to handle multiple circuits sharing a common ground in a power FTU?

Multiple circuits sharing a common ground can easily lead to mutual interference, necessitating zoning and isolation. The system is divided into four zones: power ground, digital ground, analog ground, and communication ground. Power ground is used for power supplies and motor drives; digital ground for the CPU and logic circuits; analog ground for sampling and ADC; and communication ground for RS485/Ethernet. Each zone is connected at a single point via a PBZ1608E600Z0T ferrite bead or a 0Ω resistor. The PCB design uses a segmented ground plane with a 2mm spacing, and isolation devices such as the ADUM1410 are used for signals crossing zones. The chassis ground is connected separately to earth ground. This approach reduces ground noise coupling by 25dB, allows each circuit to operate independently, and meets the IEC 61000-4-6 conducted immunity test requirements.