Quectel QuecOpen AG521R-NA Hardware Design page 72

Figure 34: Coplanar Waveguide Design on a 4-layer PCB (Layer 3 as Reference Ground)
Figure 35: Coplanar Waveguide Design on a 4-layer PCB (Layer 4 as Reference Ground)
To ensure RF performance and reliability, the following principles should be complied with in RF layout design:
⚫ Use an impedance simulation tool to accurately control the characteristic impedance of RF traces to 50 Ω.
⚫
The GND pins adjacent to RF pins should not be designed as thermal relief pads, and should be fully
connected to ground.
⚫
The distance between the RF pins and the RF connector should be as short as possible, and all the right-angle
traces should be changed to curved ones. The recommended trace angle is 135° .
⚫
There should be clearance under the signal pin of the antenna connector or solder joint.
⚫
The reference ground of RF traces should be complete. Meanwhile, adding some ground vias around RF traces
and the reference ground could help to improve RF performance. The distance between the ground vias and
RF traces should be no less than two times the width of RF signal traces (2 × W).
⚫
Keep RF traces away from interference sources, and avoid intersection and paralleling between traces on
adjacent layers.
For more details about RF layout, see document [4].
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