Q: When Esp32-S2 Sends Data Packages, The Power Value Is Much Higher Or Lower Than The Target Power Value, And The Evm Is Relatively Poor; Q: Tx Performance Is Not Bad, But The Rx Sensitivity Is Low - Espressif Systems ESP32-S2 Hardware Design Manuallines

3. PCB Layout Design
3.10.3 Q: When ESP32­S2 sends data packages, the power value is much higher or
lower than the target power value, and the EVM is relatively poor.
Analysis:
The disparity between the tested value and the target value may be due to signal reflection caused by the impedance
mismatch on the transmission line connecting the RF pin and the antenna. Besides, the impedance mismatch will
affect the working state of the internal PA, making the PA prematurely access the saturated region in an abnormal
way. The EVM becomes poor as the signal distortion happens.
Solution:
Match the antenna's impedance with the reserved π-type circuit on the RF trace, so that impedance of the antenna
as seen from the RF pin matches closely with that of the chip. This reduces reflections to the minimum.

3.10.4 Q: TX performance is not bad, but the RX sensitivity is low.

Analysis:
Good TX performance indicates proper RF impedance matching. External coupling to the antenna can affect the
RX performance. For instance, the crystal oscillator signal harmonics could couple to the antenna. If the TX and
RX traces of UART cross over with RF trace, then, they will affect the RX performance, as well. If there are many
high-frequency interference sources on the board, signal integrity should be considered.
Solution:
Keep the antenna away from crystal oscillators. Do not route high-frequency signal traces close to the RF trace.
Please see Section 3 for details.
Espressif Systems 20 ESP32-S2 Hardware Design Guidelines V1.1
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