SARA-R5 series - System integration manual
UBX-19041356 - R04
Design-in
Page 63 of 118
C1-Public
The u-blox host printed circuit board has a structure of 4 copper layers with 35
m thickness (1 oz/ft
2
)
each, using FR4 dielectric substrate material with 4.3 typical permittivity at 1 GHz, and 0.013 typical
loss tangent at 1 GHz.
The top layer layout of the u-blox host PCB designed to accommodate the
ANT
pad of SARA-R5 series
module is described in
: the left side illustrates top layer copper mask and top layer solder
resist mask, with top layer to bottom layer vias; the right side illustrates the PCB stack-up structure.
Considering that the thickness of the dielectric material from the top layer to the buried layer is larger
than 200
m, no GND keep-out is implemented on the buried metal layer area below the
ANT
pad.
Guidelines to design an equivalent proper connection for the
ANT
pad on a host printed circuit board
are available in section
ANT pad
1.5 x 0.8 mm
400
µ
m
300
µ
m
300
µ
m
RF trace
L1-L4 via
Top layer (L1) Layout
35
µ
m
35
µ
m
35
µ
m
35
µ
m
220
µ
m
220
µ
m
1200
µ
m
Top layer (L1) copper
L3 copper
L2 copper
Bottom layer (L4) copper
FR-4 dielectric
FR-4 dielectric
FR-4 dielectric
PCB stack-up structure
Figure 38: Top layer layout and stack-up structure of the u-blox host PCB for the ANT pad of the module
As illustrated on the left side of
, the antenna RF trace is routed from the RF pad on the top
layer (L1) to the bottom layer (L4) through a dedicated via. After the via, the antenna RF trace, as 50
transmission line, is connected to the antenna detection circuit described in
with the layout illustrated on the left side of
. Guidelines to design a proper equivalent
(optional) antenna detection circuit on a host printed circuit board are available in section
ANT_DET
RF trace
L1-L4 via
Bottom Layer (L4) layout
35
µ
m
35
µ
m
35
µ
m
35
µ
m
220
µ
m
220
µ
m
1200
µ
m
L1 copper
L3 copper
L2 copper
L4 copper
FR-4 dielectric
FR-4 dielectric
FR-4 dielectric
PCB stack-up structure
C2
L1
C1
D1
R1
RF trace
Figure 39: Bottom layer layout and stack-up structure of the u-blox host PCB for the antenna detection circuit