teseo liv4f antenna path

[jjoslin0994]

Hi, I am working on a senior design project at my university where we are planning to incorporate the teseo liv-4f module with the ASGPDF254.A active antenna. 

From what I see the power is pin 11 the rf_in pin the data sheet says (3v available). This leads me to believe the signal is regulated by either module as well as seen in the data sheet meaning that we can directly connect the pin 11 (liv4) <-> pin 1 (antenna) without an inductor or cap to filter the signal. 

Our professor is skeptical that it works in this manner, we are having difficulty determining which design is correct. 

The second design has the filter capacitor on the rf_in, and the choke inductors on Vcc coming from another source.

Thank you

[GalaxyQuest]

Hi Jonathan,

The RF_IN pin on LIV4F has a DC voltage bias that will power the antenna. If you are using an active antenna, then the internal LNA and SAW should be sufficient. 

We have 2 EVBS for LIV4F.

- EVB-LIV4F - https://www.st.com/en/evaluation-tools/evb-liv4f.html

we reuse the same PCB for LIV3FL (L1 only) module. Hence you see the alternate antenna path. LIV3FL unlike LIV4F does not have internal LNA and SAW.

- X-NUCLEO-LIV4A1 - https://www.st.com/en/ecosystems/x-nucleo-liv4a1.html#overview

You can connect an active antenna directly as shown in the X-NUCLEO-LIV4A1 schematic, see attachment.