Footprint for the BALF-NRF01D3?

[Sensors]

I would like to use a Balun instead of discrete components for a nrf51822 QFAA package device.

Looking at the reference designs I found a handy integrated library that included a Balun part (BAL-NRF02D3) for the CxAx package, but none for the QFAA.

Is there a similar integrated library available to the public that incorporates the BALF-NRF01D3 part/footprint for use with QFAx packages?

[Øyvind Karlsen]

Hi,

First off have a look at the general PCB design guidelines, they contain a lot of useful information that will help you get the best possible RF performance. If you need assistance tuning your circuit contact the support team engineers via mypage.

You need a balun that is compatible and made for your package. See the datasheet for the BALF-NRF01D3 for reference designs. Unfortunately there is no similar library with this balun available, maybe you could try contacting ST directly?

Make sure that you add a pi matching network between your balun and antenna!

Best regards,

Øyvind

[Sensors]

Thanks for the answer! I've made a footprint based on the datasheet now. Usually I'd be okay with doing that, but with I've never used a BGA part in a design before so I'm more cautious.

I noticed on Page 4 of the datasheet for the Balun, there are no additional components between it and the antenna. Does this mean a pi network isn't required? www.st.com/.../DM00055606.pdf

[Øyvind Karlsen]

No a pi network is definitely needed, although the makers of the balun and the antenna will say that both their products are matched to 50ohm this is only the case for a very specific scenario. If you want to have any kind of long range performance you have to add a pi network. For a practical example you can find any antenna and hook it up to a network analyzer, try moving your hand close to the antenna and see how much the impedance changes.

To reiterate, see the general PCB design guidelines, this is very well covered here.

Use a pi network.

[Sensors]

Thanks for the clairfication!

[Natab]

Is this what you're looking for? www.snapeda.com/.../