Integration Manual

SARA-R4/N4 series - System Integration Manual
UBX-16029218 - R13 Design-in Page 67 of 119
2.4.2.2 Guidelines for ANT_DET layout design
Figure 36 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
35 and Table 25:
• The ANT pin must be connected to the antenna connector by means of a 50 Ω 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) must be placed in series to the 50 Ω RF line.
• The ANT_DET pin must be connected to the 50 Ω transmission line by means of a sense line.
• Choke inductor in series at the ANT_DET pin (L1) must be placed so that one pad is on the 50 Ω 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 must be placed as ESD protection.
• The additional high pass filter (C3 and L2) on the ANT line are placed as ESD immunity improvement
SARA m odule
C2
R1
D1
C1
L1
J 1
C3 L2
Figure 36: Suggested layout for antenna detection circuit on application board