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Shay
Associate II
July 31, 2024
Solved

ST25R3916B one antenna detailed schematics

Hello,

 

I inherited a ST25R3916B design with two antennas.

I need to change the design to one antenna interface.

Is there any detailed schematic with ST25R3916B and one antenna?

Thanks

Shay

This topic has been closed for replies.
Travis Palmer
Travis PalmerBest answer
ST Employee
August 7, 2024

Hello Shay,

 

Below my comments due to your schematic from ‎2024-08-04 02:07 AM.

Decoupling caps:

You have both decoupling pairs on VDD_DR and VDD_RF. You could put C30 and C31 to d.n.p. only one pair of decoupling caps is required here. To have a spare footprint for C30 and C31 is a good idea. C17 and C18 should be as close as possible to the pins 14, 12, 16.

C32 is 10nF. The recommendation is 100nF, but this value is dependent on your supply. 

If you want to use the new wave shaping feature of the 3916B you do no need C22 assembled => d.n.p. (further details: AN5965).

C42 and C43 seems a bit high -  without knowing the xtal parameters. please have a look at AN6134.

R33 and R77 are terminating via 50Ohm the TAD's to GND. this is not required. => d.n.p.

Matching network:

The topology seems fine. You should check/measure the RFI voltage once you receive the HW. Maybe C11 needs to be adjusted.

I cannot state about the other component values.

 

BR Travis

 

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5 replies

Peter BENSCH
Peter BENSCH
ST Technical Moderator
July 31, 2024

For example, you can orientate yourself on the design of the X-NUCLEO-NFC08A1, which works with one antenna.

Hope that helps?

Good luck!
/Peter

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ShayAuthor
Associate II
July 31, 2024

Hi Peter,

 

The above design uses the device two channels (RFO1/2 and RFI 1/2), I thought there is an implementation with one channel as in the DS (see below).

Is it better to use the two channels with one antenna?

Shay_0-1722421948966.png

Thanks

Shay

 

 

Peter BENSCH
Peter BENSCH
ST Technical Moderator
July 31, 2024

You can drive the antenna either differential or single. As you mentioned, the X-NUCLEO-NFC08A1 works differentially, which is why RFO1/2 and RFI1/2 are used. If you want to use single driving, you only use either RFO1/RFI1 or RFO2/RFI2 and set the corresponding bits (IO configuration register 1, bits 7 and 6).

Hope that helps?

Regards
/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.
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