ML865G1 HW Design Guide
1VV0301632 Rev. 4
Page
66
of
86
2020-09-23
8.
GNSS SECTION
ML865G1 module includes a state-of-art receiver that can simultaneously search and track
satellite signals from multiple satellite constellations. This multi-GNSS receiver uses the
entire spectrum of GNSS systems available: GPS, GLONASS, BeiDou, Galileo, and QZSS.
GNSS Signals Pin-out
RF Front End Design
The ML865G1 Module doesn’t contain the LNA needed to reach the maximum sensitivity.
Active antenna (antenna with a built-in low noise amplifier) must be used and must be
supplied with proper bias-tee circuit.
8.2.1.
Guidelines of PCB line for GNSS Antenna
•
Ensure that the antenna line impedance is 50ohm.
•
Keep the antenna line on the PCB as short as possible to reduce the loss.
•
Antenna line must have uniform characteristics, constant cross section, avoid
meanders and abrupt curves.
•
Keep one layer of the PCB used only for the Ground plane, if possible.
•
Surround (on both the sides, over and under) the antenna line on PCB with Ground,
avoid having other signal tracks facing directly the antenna line of track.
•
The ground around the antenna line on PCB has to be strictly connected to the
Ground Plane by placing vias once per 2mm at least.
•
Place EM noisy devices as far as possible from antenna line.
•
Keep the antenna line far away from power supply lines.
•
Keep the antenna line far away from GSM RF lines.
•
If you have EM noisy devices around the PCB hosting the module, such as fast
switching ICs, take care of the shielding of the antenna line by burying it inside the
layers of PCB and surround it with Ground planes, or shield it with a metal frame
cover.
•
If you do not have EM noisy devices around the PCB hosting the module, use a
strip-line on the superficial copper layer for the antenna line. The line attenuation will
be lower than a buried one.
Pin
Signal
I/O
Function
Type
37
ANT_GNSS
I
GNSS Antenna (50
ohm)
CMOS
1.8V
33
GNSS_LNA_EN
O
GNSS External LNA
Enable
