PCB board to transform single ended to differential with a Transformer: RF help

[anpiri]

Hi all,
I am working on a project that requires 8 channel signal being converted into 8 differential signal using ‘Balun’s’ or transformers. This is because I need to connect 8 antenna's that are single ended to an FPGA ZCU208 evaluation board that has differential inputs. I am not experienced with RF components, and so I lack knowledge to ensure this conversion is done correctly. Any help regarding isolation, trace sizes and general board design would be appreciated.

I have made a basic 2 layer PCB design based on a schematic I found online for a transformer evaluation board using the components;
1) TCM2-63WX+; 1:2 CORE & WIRE Transformer, 30 - 6000 MHz, 50Ω | TCM2-63WX+ | Mini-Circuits
2) 0.5 PF capacitor
3) SMA edge connectors for the input and outputs. I designed the footprint for this SMA myself and based it off the mechanical dimensions.

My question is, what other things should I be thinking about to reduce crosstalk and any other problems? Trace width? I know we expect to be using around 5Ghz signals. Any advice regarding current spacing and trace widths would be appreciated.

My schematic has been included where it is 8 of the same circuit, and the current pcb layout included as well. Would one ground plane and one copper plane be good enough? Should the signal trace be thicker than all?

There is the PCB layout for the evaluation board provided, so I tried to replicate it and place 8 on the same pcb essentially as in a second design (image provided of close up pcb designed).

FPGA eval board link: https://docs.amd.com/v/u/en-US/ug1410-zcu208-eval-bd
Transformer link: https://www.minicircuits.com/WebStore/dashboard.html?model=TCM2-63WX+
Transformer eval board PCB layout: https://www.minicircuits.com/pcb/98-pl380.pdf

 

[FvM]

How do you want to connect your board to ZCU208 eval-board? ZCU208 is exposing balanced RF ADC and DAC in- and outputs through Samtec mezzanine connectors rather than individual SMA. Thus I expect your board to look similar to XM655 breakout board.

 

[BigBoss]

If you screen each channel, you avoid crosstalk. Trackwidths are surely important but GND Connections and VIA's are most important.
You have to carefully design this board. You should simulate -if it's possible- before implement.

 

[rf_engineer_5]

To add to the above you should consider using CPWG traces rather than what looks to be microstrip. CPWG will provide better trace shielding. Screening, meaning physical barriers between circuits as well. Out to 5GHz is harder here so best of luck. 3D simulate where possible.