Ground splitting for Custom PCB with two transceivers

[Lynn Zhou]

Hello expert,

I would like to design a custom PCB that has two transceivers on it. One transceiver is working as a beacon/continuous wave generator (TX) and the other one works as a continuous receiver (RX) and sometimes as a BLE slave. I would like to use 52833 as the receiver and haven't decided which chipset for the transmitter yet.

I have a question regarding the possible PCB design. I think I would do a 4-layer board design with relatively compact component placement.  If you regard the two modules as a whole, it's like a full-duplex system. Self-interference leakage from TX to RX seemed can not be totally avoided. Whatmore, I would like to add some SPI and I2C peripheral sensors which may also cause interference to my RX on a compact design. Will it be helpful to eliminate these issues if I split the digital ground, TX ground, and RX ground as well as TX/RX power plane?

Could anyone give me some suggestions on the ground/power design strategy?

Thank you so much!

Best regards,

Lynn Z

[ketiljo]

The performance of the antennas will be better if you have a ground plane that's as large as possible. This is especially important on small designs It's not the ground plane that will cause interference. 

If you intend to operate both the RX and the TX in the same frequency band, the RX will not be able to receive anything while the TX is operating. The coupling between the two antennas will be too great on a small board. So if the TX is operating continuously, the RX will not function. You can't use a filter either. 

[Lynn Zhou]

Thanks for your reply. 

We are not willing to receive any data packet from anyone when the full-duplex TX/RX is running. We want to use it as a small sensing radar. Thanks for reminding. I'm not willing to put two antennae on the same board but using a cable to connect them. 

So you don't think it's necessary to do TX/RX ground separation or any digital/analog ground separation? 

[ketiljo]

I wouldn't separate the ground planes.