User's Manual

AHS3-W Hardware Interface Overview
5.2 GPS Antenna Interface
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AHS3-W_HIO_v02.540a Page 31 of 41 2012-09-05
Confidential / Preliminary
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5.2 GPS Antenna Interface
In addition to the RF antenna interface AHS3-W also has a GPS antenna interface. The GPS
antenna installation and connector are the same as for the RF antenna interface (see Section
5.1.1 ).
It is possible to connect active or passive GPS antennas. In either case they must have 50Ohm
impedance. The simultaneous operation of GSM and GPS has been implemented.
AHS3-W provides the supply voltage VGPS for the GPS active antenna (3.05V). It has to be
enabled by software when the GPS-receiver shall becomes active, otherwise VGPS should be
off (power saving). VGPS 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_GPS_DC for coupling into
the GPS antenna path. Figure 6 shows the flexibility in realizing the power supply for an active
GPS antenna by giving two sample circuits realizing the supply voltage for an active GPS an-
tenna - one with short circuit protection and one with an external LDO employed.
Figure 6: Supply voltage for active GPS antenna
Short circuit
protection
(Imax=50mA)
VGPS
ANT_GPS
Active
GPS
antenna
10nH
47pF
2p2
Module
SMT interface
ANT_GPS_DC
typ 3.05V max. 300mA
Not short circuit protected!
1uF
(Optional)
ESD
protection
10k
Supply with short circuit protection
LDO
VGPS
ANT_GPS
Active
GPS
antenna
10nH
47pF
2p2
Module
SMT interface
ANT_GPS_DC
1uF
(Optional)
ESD
protection
10k
Enable
External
voltage
Supply with external LDO employed