User's Manual

PXS8 Hardware Interface Description
5.2 GNSS Antenna Interface
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PXS8_HD_v03.000 Page 32 of 41 2012-11-30
Confidential / Preliminary
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5.2 GNSS Antenna Interface
In addition to the RF antenna interface PXS8 also has a GNSS antenna interface. The GNSS
antenna installation and connector are the same as for the RF antenna interface (see Section
5.1.1). For use with GPS and GLONASS it is recommended to use a GPS and GLONASS ca-
pable antenna.
It is possible to connect active or passive GNSSS antennas. In either case they must have 50
Ohm impedance. The simultaneous operation of GSM/CDMA and GNSS has been implement-
ed.
PXS8 provides the supply voltage VGNSS for the GNSS active antenna (3.05V). It has to be
enabled by software when the GNSS receiver shall becomes active, otherwise VGNSS should
be off (power saving). VGNSS is not short circuit protected. This will have to be provided for by
an external application. The DC voltage should be fed back via ANT_GNSS_DC for coupling
into the GNSS antenna path. Figure 6 shows the flexibility in realizing the power supply for an
active GNSS antenna by giving two sample circuits realizing the supply voltage for an active
GNSS antenna - one with short circuit protection and one with an external LDO employed.
Figure 6: Supply voltage for active GNSS antenna
Short circuit
protection
(Imax=50mA)
VGNSS
ANT_GNSS
Active
GNSS
antenna
10nH
47pF
2p2
Module
SMT interface
ANT_GNSS_DC
typ 3.05V max. 300mA
Not short circuit protected!
1uF
(Optional)
ESD
protection
10k
Supply with short circuit protection
LDO
VGNSS
ANT_GNSS
Active
GNSS
antenna
10nH
47pF
2p2
Module
SMT interface
ANT_GNSS_DC
1uF
(Optional)
ESD
protection
10k
Enable
External
voltage
Supply with external LDO employed