Reference Circuit Design For Gnss Active Antenna; Gnss Rf Design Guidelines - Quectel SC200K Series Instruction Manual

5.1.3.2. Reference Circuit Design for GNSS 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. Despite its low power consumption, the active antenna
still requires stable and clean power supplies. Therefore, it is recommended to use high-performance
LDO to power the antenna. A reference design of the GNSS active antenna is shown below.
ANT_GNSS
Module
Figure 33: Reference Circuit Design for GNSS Active Antenna
NOTE
It is strongly recommended to reserve the π-type attenuation network.

5.1.4. GNSS RF Design Guidelines

Improper design of antenna and layout may cause reduced GNSS receiving sensitivity, longer GNSS
positioning time, or reduced positioning accuracy. In order to avoid this, please follow the reference
design rules as below:
⚫
Maximize the distance between the GNSS antenna and the GPRS RF part (including trace routing
and antenna layout) to avoid mutual interference.
⚫
In user systems, GNSS RF signal lines and RF components should be placed far away from
high-speed circuits, switched-mode power supplies, power inductors, the clock circuit of single-chip
microcomputers, etc.
⚫
For applications with a harsh electromagnetic environment or with high requirement on ESD
protection, it is recommended to add ESD protection diodes for the antenna interface. Only diodes
with ultra-low junction capacitance such as 0.5 pF can be selected. Otherwise, there will be effects on
the impedance characteristic of the RF circuit loop or attenuation of the bypass RF signal may be
caused.
⚫ Control the impedance of either feeder line or PCB trace to 50 Ω, and keep the trace length as short
as possible.
SC200K_Series_Hardware_Design
3V3
R2 R4
0R 0R
C4
C5
R3
NM NM
NM
Active Antenna
R1
C1 C2
10R
1 μF
100 pF
L1
56 nH
C3
100 pF
R5
NM
Smart Module Series
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