Skip to main content
77volatile77
Visitor II
July 22, 2023
Solved

STM32WB10CC RF output stage design question

  • July 22, 2023
  • 1 reply
  • 1704 views

Hello, 

For a personal project, I am designing a device that receives GPS data and transmits the UTC time information to other devices over BLE. I will also be designing a device that receives the data and displays it. For this, I have chosen the STM32WB10 MCU. I think I have a surface-level knowledge of RF, but I couldn't understand this application schematic in AN5290, page 10:

 

77volatile77_0-1690045960408.png

What I am confused about is the low pass filter at the end. Assuming I connect an antenna to the RF output, how would this device work in RX mode? Perhaps as a result to my inexperience with RF, the antenna being connected to the output of the LPF doesn't make sense to me. The same circuit is also showed in AN5165, page 13. 

Thank you in advance for the advice. 

This topic has been closed for replies.
Best answer by Nikita91

The RF1 pin is not an output pin, but a RX/TX pin. The antenna is used for both.

The filter works in both directions, but its characteristics are not quite symmetrical, hence the terms input/output. It must be soldered the right way.

1 reply

Nikita91
Nikita91Best answer
Lead II
July 23, 2023

The RF1 pin is not an output pin, but a RX/TX pin. The antenna is used for both.

The filter works in both directions, but its characteristics are not quite symmetrical, hence the terms input/output. It must be soldered the right way.

Terms & ConditionsAccessibility statement