SARA-G3 and SARA-U2 series - System Integration Manual
UBX-13000995 - R26
Design-in
Page 127 of 217
2.4.2.2
Guidelines for ANT_DET layout design
Figure 61 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 60 and Table 39.
SARA-G340 / SARA-G350
SARA-U2 series module
C2
R1
D1
C1
L1
J1
C3 L2
Figure 61: Suggested layout for antenna detection circuit on application board
The antenna detection circuit layout suggested in Figure 61 is explained below:
The
ANT
pin is 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 the
ANT
pin (C2) is placed in series to the 50
transmission line.
The
ANT_DET
pin is connected to the 50
transmission line by means of a sense line.
Choke inductor in series at the
ANT_DET
pin (L1) is 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 are placed as ESD protection.
The additional high pass filter (C3 and L2) on the
ANT
line are placed as ESD immunity improvement for
SARA-U260, SARA-U270 and SARA-U280 modules (a series 0
jumper can be mounted for SARA-G340
and SARA-G350 modules instead of the high pass filter, as no further precaution to ESD immunity test is
needed).
