Antenna Matching for the nRF52840

[tdudziak]

I have looked all over the product specification and the website and cannot find any information related to matching an antenna for this device. 

What I am looking for are the characteristics of PIN P$H23/ANT. Once I get this I can take it from there. 

Can anyone help? 

Thanks in advance.

[Kenneth]

Hello,

I will use the nRF52810 as an example on how to add any 2.4GHz antenna, first you start with the reference design for the nRF52810 as shown here (in your case you should start with the reference design for the nRF52840):
https://infocenter.nordicsemi.com/topic/ps_nrf52810/ref_circuitry.html#concept_hqh_j22_fq 

You can see that the ANT matching consist of 2 components (L1/C3) that ensure a 50ohm feed point labeled "RF". The antenna and matching for the 2.4GHz antenna must be placed after this point. For an example on how to add an antenna you can look at this design with the nRF52810 (you can see there are 3 components added for the antenna tuning (C14/R17/L4), often referred to as a PI-network). Actual components values are found during tuning:
https://infocenter.nordicsemi.com/topic/ug_sr3_nrf52/UG/sr3_nrf52/hw_descr_prod_ex/antenna.html

The same PI-network must also be added for a design with the nRF52840 (or any other nRF device). This PI-network ensure you can tune any antenna to 50ohm, as shown and described in the Antenna tuning (e.g. chapter 4.2): 
https://infocenter.nordicsemi.com/pdf/nwp_017.pdf 

I also encourage you to read the PCB guidelines (I link to the nRF52840 in this case, but same applies for other nRF devices):
https://infocenter.nordicsemi.com/topic/ps_nrf52840/ref_circuitry.html#concept_hf5_hzm_fs 

Best regards,
Kenneth

[tdudziak]

Thank you. I think I have the information I was looking for.