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Visitor II
May 4, 2025
Question

Request for Hardware RF design guide for STM32WL

  • May 4, 2025
  • 1 reply
  • 466 views

Dear ST Support Team,

I hope this message finds you well.

I am currently working on a custom RF design using the STM32WLE5CCU6 in UFQFPN48 package, and I intend to operate in the 433 MHz ISM band with +22 dBm output power.

While referring to Application Note AN5457, I found valuable information and examples for PA output matching networks and impedance values extracted via load-pull analysis. However, it appears that the document does not provide any reference impedance data or matching guidelines for 433 MHz at high power levels (+22 dBm) for this specific MCU and package.

Therefore, I would like to ask:

What is the optimal output impedance (complex conjugate of the load) for the PA in this configuration (433 MHz, +22 dBm, UFQFPN48)?

How can I accurately calculate or measure the required PA matching network (L1, C1 values) to transform this impedance to 50 Ω, considering high efficiency and minimal power loss?

The circuit I used for impedance matching is as follows:

5.PNG

Only the values ​​you see in the figure are not accurate.

If possible, please advise the values ​​of the inductors and capacitors for a frequency of 433 MHz, I would be grateful.

Could you please provide any additional design guidance or references (e.g., matching component values, Smith chart locations, simulation models) for this specific configuration?

Your assistance is greatly appreciated, as this information is critical for ensuring the RF performance and reliability of the design.

Looking forward to your support.

1 reply

STTwo-32
Technical Moderator
May 22, 2025

Hello @Mostafa_fatehi 

For the values about the RF matching network, the AN5457 should guide you following the examples and rules to determine the PA matching. For design review and reference designs, I suggest you take a look on my answers for the following two posts:

Best Regards.

STTwo-32