EVK-M8GZOE User Guide
UBX-16030132 - R04
Device description
Page 13 of 30
Early Production Information
☞
Do not use both GNSS inputs at the same time. Either use the passive (simulator) or use the
active antenna input.
Figure 3: EVK-M8GZOE schematic of GNSS inputs
There is a RF switch (U14) which only allows one of the 2 GNSS signal inputs to ZOE-M8G.
Active antenna input
The active antenna input provides 3.3 V supply for active antenna. There is a current limiter circuitry
that limits the maximum current to about 50 mA. Besides the current limiter, there is also a current
detector circuit which has the threshold at 5 mA. That is how the RF switch (U14) is set if the active
antenna Input goes to ZOE-M8G or the Simulator input.
☞
Only if current drawn at active antenna input is more than 5 mA, it can be used.
4.3.1.1
Direct ZOE-M8 GNSS performance
There is also an option to have the active antenna input available without connecting an active
antenna. In that case jumper J8 has to be populated, see Figure 2 and Figure 3. Having jumper J8
populated ensures a current draw at active antenna Input and thus the RF switch will still stay at the
active antenna Input.
Thus a passive antenna or simulator can be connected and performance can be verified when have
no external LNA in front of ZOE-M8 modules.
☞
There is DC at the active antenna Input, consider to use a DC block.
1.1.1
Simulator input
At simulator input there is an external LNA (U12) used in front of ZOE-M8G to show optimal GNSS
performance. This allows verifying datasheet values of ZOE-M8 modules with a GNSS simulator.
☞
Only if NO current is drawn at active antenna Input (< 5 mA), the simulator Input can be used.
Ensure no active antenna is connected to active antenna input and jumper J8 is not populated.
