Regarding nRF51822 RF range using balun and minimum layers required for balun

[Shahid Ali Nadaf]

Hi,

I am doing a BLE based project using NRF51822. I am asked to build a 2 layer board.

According to the reference schematic BALF-NRF01D3 has been used with WLCSP package. Since this balun is difficult to mount at my expense can you suggest me any other balun with QFAA package and similar properties and range.

I read the following post devzone.nordicsemi.com/.../

But here i am not able to understand what range can i expect by using nRF51822/422 QFN and discrete components for matching(pi network).

nRF51822/422 QFN - www.johansontechnology.com/integrated-passives/chipset-specific-ipc/nordic-semiconductor.html#.VOW78pjuKRt

Another Question:- Can balun be mounted on 2 layer board?? Or a 4 layer board is required to mount a balun??

Looking forward your suggestion.

[Asbjørn]

You can use a 2 layer board to implement the balun as well. Keep in mind that in nRF51822-PCN we state that using the BAL_NRF01D3 with our nRF51822-QFAA/AB are likely to fail Korean requirements with regard to spurious.

Designs based on nRF51822-QFAA/nRF51822-QFAB combined with ST Microelectronics balun, BAL-NRF01D3 (as described in the reference layout nRF51822-DF-ST v1.0), are likely to fail Korean teleregulatory spurious emission limits due to LO leakage.

You would have to ensure that the track width are 50 Ohm from the output of the balun towards the antenna based on the parameters of your board.