Q: The Voltage Ripple Is Not Large, But The Tx Performance Of Rf Is Rather Poor; Q: The Voltage Ripple Is Small, But Rf Tx Performance Is Poor; Q: When Esp32-H2 Sends Data Packages, The Power Value Is Much Higher Or Lower Than The Target Power Value, And The Evm Is Relatively Poor - Espressif Systems ESP32-H2 Series Hardware Design Manuallines

3 PCB Layout Design

3.8.1 Q: The voltage ripple is not large, but the TX performance of RF is rather poor.

Analysis:
The voltage ripple has a strong impact on the RF TX performance. It should be noted that the ripple must be
tested when ESP32-H2 is in the normal working mode. The ripple increases when the power gets high in a
different mode.
Generally, the peak-to-peak value of the ripple should be <80 mV when ESP32-H2 sends MCS7@11n packets,
and <120 mV when ESP32-H2 sends 11m@11b packets.
Solution:
Add a 10 µF filter capacitor to the branch of the power trace (the branch powering the chip's analog power pin).
The 10 µF capacitor should be as close to the analog power pin as possible for small and stable voltage
ripples.

3.8.2 Q: The voltage ripple is small, but RF TX performance is poor.

Analysis:
The RF TX performance can be affected not only by voltage ripples, but also by the crystal itself. Poor quality and
big frequency offsets of the crystal decrease the RF TX performance. The crystal clock may be corrupted by
other interfering signals, such as high-speed output or input signals. In addition, high-frequency signal traces,
such as the SDIO traces and UART traces under the crystal, could also result in the malfunction of the crystal.
Besides, sensitive components or radiating 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 3.4 for
details.
3.8.3 Q: When ESP32-H2 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.
Espressif Systems 26
ESP32-H2 Series Hardware Design Guidelines v0.5
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