ZOE-M8 series - Hardware Integration Manual
UBX-16030136 - R07 Production Information Design-in
Page 12 of 32
GLONASS L1OF, Galileo E1B/C and BeiDou B1) can be received and processed concurrently. This concurrent
operation is extended to 3 GNSS systems whenever GPS and Galileo are used in addition to GLONASS or BeiDou.
2.5.1 Passive antenna
ZOE-M8 SiPs are optimized to work with passive antennas. The internal SAW filter inside followed by an LNA is a
good compromise for most applications from jamming and performance point of view.
Figure 4: Typical circuit with passive antennas
Where best performance needs to be achieved and no jamming sources are present, an LNA (U1) can be placed
close to the antenna.
Figure 5: Circuit for best performance
The LNA (U1) can be selected to deliver the performance needed by the application in terms of:
• Noise figure (sensitivity)
• Selectivity and linearity (robustness against jamming)
• Robustness against RF power and ESD
The external LNA (U1) must be placed close to the passive antenna to achieve best performance.
The LNA_EN pin can be used to turn off the external LNA.
ESD discharge into the RF input cannot always be avoided during assembly and / or field use with this approach!
To provide additional robustness, an ESD protection diode, as listed in Appendix A.6, can be placed in front of the
LNA to GND.
If the VCC supply is also used to supply the external LNA, make sure some good filtering is in place for
the external LNA supply because of the noise on the VCC. This means that a series ferrite bead FB1, see
section A.7, and a decoupling capacitor to GND must be used.
To Next Page
Loading...
Need help?
General
