udi-eng
Junior Member level 1

Hello,
I am trying to layout the RF part of ST's Lora chip STM32WL55CC based on their reference design(NUCLEO-WL55JC).
There are some things that are very unclear to me based on their design:
1) they clearly laid out the RF part with impedance consideration, however: when I calculate the impedance I get:
- values that are different from 50 ohm.
- different values for different parts of the "rf chain", that is: It seems like there are a lot of impedances from TX output pin to antena.
The chip datasheet states:
* All RF impedances matched using reference design
* Transmit mode output power defined in 50 Ω load
I added relevant files to see the issues I am discussing.
I am trying to layout the RF part of ST's Lora chip STM32WL55CC based on their reference design(NUCLEO-WL55JC).
There are some things that are very unclear to me based on their design:
1) they clearly laid out the RF part with impedance consideration, however: when I calculate the impedance I get:
- values that are different from 50 ohm.
- different values for different parts of the "rf chain", that is: It seems like there are a lot of impedances from TX output pin to antena.
The chip datasheet states:
* All RF impedances matched using reference design
* Transmit mode output power defined in 50 Ω load
I added relevant files to see the issues I am discussing.
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