PCB design problem with Bluenrg-332ac

[JasonYang]

Hi everyone,

I am currently designing my own PCB board using the bluenrg-332ac chip. I want to use the ufl/SMA port to connect my antenna without connecting the PCB antenna. So I wonder how to remove the PCB antenna from the PCB layout with only UFL port? as the PCB guideline didn't show me how to configure the matching network for the UFL port.

Also, the current ufl port on the eval board is only for testing the chip's functionality and has a very low RSSI, which makes the signal too weak to be used.

Thank you.

Reference files: AN5526  STEVAL-IDB012V1 

[Laurent LOUAZON · Accepted solution]

Hello,

On our evaluation kit, in order to connect your antenna plugged on uFL connector you simply need to unsolder C20 and set it on the capacitor in direction of uFL connector.

If willing to design your own PCB, please keep the same schematic but you will have to define values (for C11/L5/C10) that will allow to match your own antenna.

Regards

Laurent

[JasonYang]

Hi Laurent,

Thank you for your answer! I also want to ask what the black "X" means, plotted on the matching network C11 and C10. Does that mean the capacitor is optional?

Best,

Jason

[Laurent LOUAZON]

Hello,

C11 and C12 are not used (not mounted). It means there were not needed to match our printed antenna.

In your case, depending the antenna you will use (but also depending PCB structure or mechanical parts surrounded your PCB) , you will have to define few components to match your antenna and be sure it behaves properly @2.45GHz.
So you should add three components such as C11/L5/C10 on your PCB, then define the right values measuring S11 with a Vector Network Analyser to be sure your antenna is matched.

Regards
Laurent

[JasonYang]

Hi,

In my case, I only connect my antenna to the UFL connector externally instead of placing the antenna on the PCB. So, do I still need to design a matching network in front of the ufl connector? (I thought only a C20 was needed)

Best,

Jason

[Laurent LOUAZON]

Hi,

When using our evaluation kit and using an external antenna connected to uFL connector, just setting C20 will be fine.

Reason is that such external antenna are 50oHms and large band.

My comment about adding few components for antenna matching is for the case you design your own PCB with a printed antenna .

Laurent