Specifications

Module：EWN-8822CSS3AH
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13.2 SDIO Interface
The SDIO interface has 4 data lines, a cock signal line and a command signal line. all of the
SDIO lines must be equal length. In order to avoid mutual interference, SDIO lines should be
avoided to be adjacent and parallel to other data lines, RF lines and power lines, and Surround
the data line and clock line with ground copper.
13.3 RF circuit
Due to the SMD package, the RF port impedance must be offset after the module is soldered
to the motherboard. In order to achieve the best performance,, it is recommended to add a
PI-type matching network to the motherboard, as shown below (C11, R21,C6). The value of the PI
type matching network needs to be debugged according to the actual motherboard to match RF
port impedance to 50 Ohm.
FIG 17 Connect 50 Ohm matching antenna reference circuit
The antenna ANT1 in the figure above must be 50 Ohm. If the antenna is not matched, it is
recommended to add a set of PI type matching network at the front of the antenna to match the
antenna. Generally, the antenna manufacturers will give Suggestions on matching parameters.
FIG 18 Connect the unmatched antenna reference circuit
The RF line layout should be matched according to 50ohm. The line impedance is related to
the plate, plate thickness, line width and copper spacing. Professional software can be used to
calculate the line width. Note: for multilayer plates, the plate thickness should calculate the