STM32WLE5JC Receiver Chain

[KTrot.1]

Hi !

I read the datasheet, and it says:

"The receive chain comprises a differential low-noise amplifier (LNA), a down-converter to
low-IF by mixer operation in quadrature configuration".

1. What is the GAIN and the NF of the diff. LNA ?

      1.a Is it also the NF of the LORA ?

2. Can I add another amplifier (LNA) at the input ?

Thanks,

Kosta

[STTwo-32 · Accepted solution]

Hello @KTrot.1 

The NF has been measured following the procedure described below using the RSSI:

SNR_in = pwr_in_RX+ 174 = 94dB
SNR_out= RSSI (gene ON) – RSSI (gene OFF) + 10*log (BW)
NF=SNR_in – SNR_out.
NF doesn't depend on modulation.

For example: 

For a frequency of 868 MHz

Gain = 41 at 25° and 3.3V (highest LNA gain step).

NF = 5.6 at 25° and 3.3V SMPS ON

For the external LNA: for low data rate or high SF (for LoRa) I'm not sure it's interesting, for higher data rate it should be possible to gain several dB of sensitivity, in fact I don't see why it should not be possible.

Best Regards.

STTwo-32