UBX-G7020 - Hardware Integration Manual
Design-in
GPS.G7-HW-10003
Objective Specification
Page 37 of 74
ESD discharge can’t be avoided during assembly and / or field use. Note also that SAW filters are susceptible to
ESD damage.
The PIO16 (ANT_OFF_N) can be used to enable and disable the external LNA for improved power savings, e.g. in
Power Save Mode. To enable this, PIO16 must be configured via the Low Level Configuration to provide the
ANT_OFF function with the correct polarity - ANT_OFF_N signal. This configuration is part of the antenna
supervisor section within the Low Level Configuration, see section 2.10.2.
A pull-down resistor (R7) is required to ensure correct operation of the ANT_OFF_N signal at PIO16.
2.6.2.4
RF front-end using an active antenna
Active antennas for GPS/GNSS application are usually powered through a DC bias on the RF cable. A simple bias-
T as shown in Figure 20 can be used to add this DC current to the RF signal line.
Figure 20: Active Antenna Supply circuit (Bias-T)
L3 isolates RF from the DC path and C17 removes high frequency noise from the DC supply. R4 serves as a
current limiter and should be dimensioned to dissipate the power generated by a short on the antenna input.
Also, L3 should be selected to pass the DC fault current.
The UBX-G7020 supports antenna supervision by adding external circuitry. For more information please
see section 2.2.7.
Make sure the DC block (C1) is in place; the UBX-G7020 LNA_IN has no internal DC block.
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