SARA-R4 series - System Integration Manual
UBX-16029218 - R06
Design-in
Page 58 of 102
2.4.2.2
Guidelines for ANT_DET layout design
Figure 25 describes the recommended layout for the antenna detection circuit to be provided on the application
board to achieve antenna detection functionality, implementing the recommended schematic described in the
previous Figure 24 and Table 20:
The
ANT
pin has to be connected to the antenna connector by means of a 50
transmission line,
implementing the design guidelines described in section 2.4.1 and the recommendations of the SMA
connector manufacturer.
DC blocking capacitor at
ANT
pin (C2) has to be placed in series to the 50
RF line.
The
ANT_DET
pin has to be connected to the 50
transmission line by means of a sense line.
Choke inductor in series at the
ANT_DET
pin (L1) has to be placed so that one pad is on the 50
transmission line and the other pad represents the start of the sense line to the
ANT_DET
pin.
The additional components (R1, C1 and D1) on the
ANT_DET
line have to be placed as ESD protection.
The additional high pass filter (C3 and L2) on the
ANT
line are placed as ESD immunity improvement
SARA module
C2
R1
D1
C1
L1
J1
C3 L2
Figure 25: Suggested layout for antenna detection circuit on application board
