NUCLEO-WL55JC2 mod to run 868Mhz

[OFauc.1]

Hi,

I have a  Nucleo-wl55jc2 (US Low Band 433 Mhz)

Would it be possible to remove the RF filters so I can run it on high frequences (EU 868 Mhz) ?

Thanks

Olivier

[OFauc.1]

By the way, I'd like ton know what would appends if I bypass the LC filters and I connect RFO_LP/RFO_HP to BGS13S4N9 RF Switch.

Thx for your help

[Pat_ST]

Hello,

The LC filters in the front end part are used adapt the impedance of the signal coming from the STM32WL transceiver and to ensure that the signal going to 

the BGS13S4N9 RF Switch is properly filtered. If you bypass the LC filters, and if you control the frequency with AT commands at 868MHz, the 868MHz 

signal at the output antenna will be present but not at its maximum power and with many spurious (especially at its harmonics). 

The sensitivity of your system will be also strongly degraded. In addition, your system will not be able to pass any RF certifications. 

In other words, your system will be basically functional at 868MHz if you bypass the LC filters, but with poor performances (lack of power, 

bad sensitivity and a lot of spurious signals) and no chance to cope with RF certifications.

You have 2 alternatives:

• Either by by a NUCLEO-WL55JC1 product, which is dedicated for EU and US frequencies (between 865MHz to 928MHz).
• Either you change the LC filters components as well as decoupling capacitors. NUCLEO-WL55JC1 schematic is also available on st.com