ESP32 Forum

Posted: **Mon Feb 27, 2023 2:34 am**

Hi,

What impedance is the LNA_IN pin on the ESP32-S3? Unlike the ESP32-S2 hardware design guide, the ESP32-S3 hardware design guide (https://www.espressif.com/sites/default ... nes_en.pdf) doesn't actually say. The -S3 design guide only says:

A π-type matching network is essential for antenna matching in the circuit design. CLC structure is recommended for the matching network. It is also recommended to add an LC filter circuit after the π-type matching network side to suppress secondary harmonics. The parameters of the components in the matching network are subject to the actual antenna and PCB layout. Figure 9 shows the RF matching schematic.

To design the matching network we would need to know the output pin impedance. We do not have a VNA so measuring the value directly is not possible.

Thanks,

Sam

Posted: **Fri Mar 03, 2023 2:44 am**

To do RF tuning, output impedance is not direct, please know S11 should be 35 ohms in ESP32-S3, use this information to tune matching parameters.

Posted: **Sun Apr 16, 2023 2:26 am**

What is the imaginary component of the ESP32-S3 impedance? Is it 35+0J as is implied by your last response? In this similar post for the ESP32-C3 chip you gave a similar answer and then clarified is was not just 35, but actually (30 to 40) +/- J10. https://esp32.com/viewtopic.php?t=21649

This would be great info to have updated in the esp32 hardware design guidelines, as right now there is no info on the 7*7 QFN S3 chips.

Posted: **Mon Sep 18, 2023 12:20 pm**

The impedance has not yet been added to the datasheet. Is there any info on this?

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