Designing my schematic and PCB with nRF51822 using balun and onchip antenna.

[Hardik]

Dear Team,

 

Can you please review the attached schematic of NRF51822 used with matching Balun and chip antenna.

 

Balun: 2450BM14E0003T

Chip Antenna: 2450AT18A100E (T matching network)

 

Please help to solve below queries:

1. Please confirm chip antenna used with a balun, will that work? Suggest matching chip antenna if I am wrong.

2. Is it ok to use R6 ( 0R ) in series with balun?

3. Pin 31 (ANT1) and Pin 32 (ANT2) are to be routed differential?

4. Please share design guidelines for Balun and Chip Antenna for good RF performance.

5. Please share the reference design for the same.

Waiting for a positive response from experts.

nrf51822.pdf

[Andreas]

Hi,

 

1. This balun can be used with pretty much any antenna. You should make sure the antenna recommended mounting(see the datasheet) is compatible with your intended monuting for optimal performance.
2. It is ok.
3. Not important, make sure you replicate the reference design shown in the datasheet of the balun.
4. Replicate reference design or recommended mounting for balun and antenna, shown in the datasheets and supplied as design files by the manufacturers. Update antenna tuning component BOM after tuning antenna. Add ground pour with plenty vias. You can find a design tutorial blog here. If you are in doubt if your design has any issues feel free to upload it in a case here for review.
5. nRF51x22 reference designs can be found here, but this is with discrete component matching networks. For reference designs see Johanson website.

 

Best regards,

Andreas

[Hardik]

Dear Andreas,

Thanks for your response.

Which matching network you suggest either PI or T network.

I have referred to the various chip antenna from Johanson Technology.

They use to recommend PI or T network with component values.

Hope selected chip antenna with T network and recommended values will work.

[Andreas]

Hi,

 

T or PI does not really matter. Theoretically only two of the components are needed (L network), but as we do not know what kind of orientation the L network will have (series-shunt or shunt-series), space for a full T/PI network should be reserved so that your design can accomodate both types. A T network will require an additionan 0 Ohm resistor in addition to the L network, which the PI network does not need and might thus be the only difference.

The suggested values will probably be better than none, but from experience you should expect these to change if you tune the antenna. We are happy to receive one of your samples and do this for you if you need.

 

Best regards,

Andreas

[Hardik]

Hi,

Thanks for your kind reponse.

Will share gerber file too for review.

Specially for matching RF antenna impedance.

[Andreas]

Hi,

 

OK, we will conduct the review as well. Feel free to submit whenever most convenient for you.

 

Best regards,

Andreas