LTE Module Series
EG21-G Hardware Design
EG21-G_Hardware_Design 60 / 100
Figure 34: 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 control the characteristic impedance of RF traces as 50Ω.
The GND pins adjacent to RF pins should 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.
There should be clearance area 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).
For more details about RF layout, please refer to
document [6]
.
5.2.
GNSS Antenna Interface
The following tables show pin definition and frequency specification of GNSS antenna interface.
Table 26: Pin Definition of GNSS Antenna Interface
Pin Name
Pin No.
I/O
Description
Comment
ANT_GNSS
47
AI
GNSS antenna
50Ω impedance.
If unused, keep it open.
