ZED-F9P - Integration Manual
UBX-18010802 - R01
5 Design
Page 43 of 64
Objective Specification - Confidential
is not a simple task and requires RF simulation and RF design expertise. It is important that
the PCB trace design uses a minimum amount of L/C passive components as these can cause
dramatic variation over temperature and component tolerance. Montecarlo 250 simulations and 5%
(Gaussian) component tolerances need to be run to confirm the affects of these L/C components.
Figure 42: Wilkinson Divider
Additional points on the RF input
If an additional LNA protection filter shall be used its bandwidth has also to be increased for
combined GNSS L1 + L2 + L band signals.
What is the expected quality of the signal source (antenna)?
• What is the external active antenna signal power?
• What is the bandwidth and filtering of the external active antenna?
Are destructive RF power levels expected to reach the RF-input? Is interference from wireless
transmitters expected?
• What are the characteristics of these signals (duty cycle, frequency range, power range,
spectral purity)?
• What is the expected GNSS performance under interference conditions?
Is there a risk of RF-input exposure to excessive ESD stress?
• In the field: Is the antenna connector accessible by the user?
• PCB / system assembly: Is there risk that statically charged parts (e.g. patch antennas) may
be discharged through the RF-input?
Is there a risk of RF-input exposure to excessive ESD stress?
• In the field: Is the antenna connector accessible by the user?
• PCB / system assembly: Is there risk that statically charged parts (e.g. patch antennas) may
be discharged through the RF-input?
The following subsections provide several options addressing the various questions above:
In some applications, such as GSM transceivers, interference signals may exceed the
maximum power rating of the LNA_IN input. To avoid device destruction use of external input
protection is mandatory.
