nRF52840 and Pin Limiter Diodes on the Bluetooth Antenna Line

RE: nRF52840 and Pin Limiter Diodes on the Bluetooth Antenna Line

hendrikB — Tue, 02 Dec 2025 13:23:50 GMT

Hi Simon

Thanks for the update and info.

Kind Regards

Hendrik

RE: nRF52840 and Pin Limiter Diodes on the Bluetooth Antenna Line

Simonr — Tue, 02 Dec 2025 13:13:16 GMT

Hi again

The main purpose of the band pass filter on the BLE radio is to reduce blocking (of the BLE radio) when it is in RX and LTE is transmitting. The nRF52 series can tolerate 10dBm on the ANT pin without any problems, so a PIN diode is not needed for that purpose.

However, in any case you should avoid transmitting with both radios at the same time, as it will greatly increase the necessary production testing and cost on your end.

The LTE harmonics are more likely to cause trouble as they are on frequencies close to the 2.4GHz band. Thus on designs like the Thingy:91X, we have an additional RF filter and an ESD diode to reduce this. Physical distance between the antennas will also help.

Best regards,

Simon

RE: nRF52840 and Pin Limiter Diodes on the Bluetooth Antenna Line

Simonr — Mon, 01 Dec 2025 14:13:29 GMT

I will need to get back to you tomorrow with a decisive reply to this question. Thank you for your patience.

Best regards,

Simon