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When the passive antenna is placed far away from the module (that is, the antenna trace is long), it is
recommended to add an external LNA circuit for better GNSS receiving performance, and the LNA
should be placed close to the antenna.
5.2.2.2. Recommended Circuit for Active Antenna
The active antenna is powered by a 56 nH inductor through the antenna's signal path. The common
power supply voltage ranges from 3.3 V to 5.0 V. Although featuring low power consumption, the active
antenna still requires stable and clean power supplies. It is recommended to use high-performance LDO
as the power supply. A reference design of the GNSS active antenna is shown below.
Active Antenna
3V3
Module
ANT_GNSS
56 nH
10R
1
μF
100 pF
NM
NM
C4
C1
R1
L1
R2
0R
C5
C3
C2
100 pF
R4
R3
R5
Figure 32: Reference Circuit Design for GNSS Active Antenna
When using external active antennas or external LNA circu
its, we recommend reserving type π
attenuation networks (R3, R4, R5) to improve GNSS reception performance.
5.2.2.3. GNSS RF Design Guidelines
Improper design of antenna and layout may cause reduced GNSS receiving sensitivity, longer GNSS
positioning time, or reduced positioning accuracy. To avoid these, please follow the reference design
rules as below:
⚫
Maximize the distance between the GNSS RF part and the GPRS RF part (including trace routing
and antenna layout) to avoid mutual interference.
NOTE
