CONFIDENTIAL
3
PCB Layout Design
result in the malfunction of the crystal oscillator. Besides, sensitive components or radiation components, such
as inductors and antennas, may also decrease the RF performance.
Solution:
This problem is caused by improper layout and can be solved by re-layout. Please see Section
for
details.
3.10.3 Q: When ESP32S3 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
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. Poor RX sensitivity may result from external
coupling to the antenna. 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
for details.
Espressif Systems
28
ESP32-S3 Series Hardware Design Guidelines v1.0
