N720 OpenLinux
Hardware User Guide
Copyright © Neoway Technology Co., Ltd
56
Reference Design of Passive GNSS Antenna
Figure 3-52 Reference Design of Passive GNSS Antenna
N720 module
Matching
Network
Matching
Network
LNA
ANT_GNSS
GNSS_LNA_EN
Close to antenna
Schematic Design Recommendations
For the impedance matching circuit between N720 and GNSS antenna, refer to section 3.5.1.
If using a passive GNSS antenna, place an LNA near the feeder because the module does not
embed one internally. GNSS_LNA_EN is used to enable the external LNA. To get a better
performance, use a multi-stage LNA.
Add a SAW filter between matching network and LNA.
PCB Design Guidelines
Place the LNA as close to the antenna as possible.
Keep GNSS antenna far away from other antennas, such as main antenna and WLAN antenna.
For more details, see section 3.5.1 ANT_MAIN/ANT_DIV antenna interface.
Reference design of active GNSS antenna
After the antenna receives GNSS satellite signals, the LNA amplifies the signals first and then transmits
them to the ANT_GNSS pin of N720 OpenLinux through feeder and PCB traces. See Figure 3-53.