nRF54L15 impedance-matching network

[ael-mess]

Hello,

I am designing a PCB using the nRF54L15 and a ceramic antenna and got confused regarding the impedance-matching network. In the detasheet a 1.5pF, 2.0pF, and 0.3pF capacitors and 2.7nH and 3.5nH inductors are used, but in the DK schematics an additional 1.4pF parallel capacitor is added before the PCB trace antenna. I also have a different circuit suggested in the antenna datasheet. How should I connect my ceramic antenna to the MCU?

Also, according to the nRF54L15 datasheet the matching network should be grounded only to the ground pad and bottom layer, but it is not the case in the DK schematics.

Best regards,

Amine

[ketiljo]

This is the latest reference design for the nRF54L15 QFAA 

The 1.4 pF cap you see on the DK is for antenna tuning. In your case, you want to place all antenna tuning components between C11 and the antenna. 

The DK may be older than the reference design. DKs version 0.9.2 and later will have the updated reference design. 

[ael-mess]

Ok, thank you for your response.

So if required, the tuning components need to be after C11, but should also the tuning components not be grounded in the top layer?

[ketiljo]

Only C6 is grounded to the bottom layer. All other components are grounded on the top layer ground plane as usual