How can ground loop be avoided when connecting two system with same ground. This happen in PC whith SATA cable or PCIe Card with seprated power cable.
My System
- Board: I have two pcb each with a ground plane. The board #1 is powered up by a battery. and through board #1, battery connected to board #2 via two wire (battery V+ and V-).
- Reciever: Reciever is WF111, a wifi module run @50MHz with SDIO
- Transmitter: Transmitter is ZYNQ-7000 a Cortex A9 processor
- Power: the processor is powered with LDO #1 (simplified) and WF111 through LDO #2(again simplified).
- Signal: the signal between transmitter and reciever connected with a FFC cable between two boards.
Question
Sending gnd for current return path as suggested here, will create big ground loop and will act as a big antenna. So what you suggest.
Best Answer
Yes you should have ground conductors in the FFC to provide a return path for the signals. Connect the cable ground to the board ground which should also be your signal ground. This is reducing the loop, not making it worse. In this kind of configuration it is common to connect the ground plane of each board to a common metal chassis.