What EMI frequencies should I filter to ensure proper operation of the nRF52833?

[Nil Orbach]

Hello everyone,

I am designing a Bluetooth repeater that will be powered eather by USB or an embedded Li-Po battery. This device will run with the nRF52833 along with a PA/LNA from Skyworks. 

The power supply sources (USB and battery) may produce EMI, leading me to design low-pass LC filters with ferrite beads. In consequence, I am wondering: which frequencies should be filtered to avoid any interference with the nRF52833? 

I have read here (https://devzone.nordicsemi.com/f/nordic-q-a/10365/gtt_2_introduction-nrf52-selectivity?pifragment-684=2) that the Intermediate Frequency of the Nordic was 1 MHz, so I guess that this frequency should be primarly filtered, is that correct? Also, is there other frequencies I should take care of for filtering?

Best regards,

Nil

[ketiljo]

Unless you are using switching regulators that are improperly filtered, there shouldn't be any need to have additional filtering. Maybe a ferrite bead in the nRF52833's and the PA/LNA power supply. 

SInce you meantion a PA/LNA, be aware that the highest output power you can use for BLE in Europe is 10 dBm.

[Nil Orbach]

Thank you a lot for your reply and your piece of advice. 

Best regards,

Nil