Bias Circuit Design For Active Antenna - Furuno GN-86F User Manual

3.2

Bias Circuit Design for Active Antenna

86/87 series module supports two ways to bias the active antenna. One is to use VCC_RF pin, which is
designed to supply the antenna power from the module, as shown at the left side in Figure 3-1. The other is
to provide from an independent antenna power (VANT) which is prepared by customer's system, as shown
in the right side.
In case of using VCC_RF, the antenna bias voltage is same with VCC voltage provided to the module by
customer's system. Therefore, if the active antenna requires different voltage like 5VDC, customer's system
needs to prepare the required voltage as VANT and feed it to the antenna connector through the inductor
as shown at the right side in Figure 3-1.
VCC_RF
RF_IN
VCC_RF
ANT_DET0
ANT_DET1
FLNA
Figure 3-1 Active Antenna Power Supply Configuration
Figure 3-2 shows the insertion of the antenna detection circuit. Details are described in Section 3.5.
FURUNO ELECTRIC CO., LTD. All rights reserved.
FURUNO GPS/GNSS Receiver 86/87 Series User's Design Guide
Active antenna
LNA
33pF
VCC
RF_IN
VCC_RF
ANT_DET0
ANT_DET1
VCC
FLNA
Figure 3-2 In Case of Using Antenna Detection Circuit
External power supply
RF_IN
VCC_RF
ANT_DET0
ANT_DET1
Antenna Biasing Circuit
Antenna
Detection
Circuit
VANT
12
SE13-900-001-06
VCC
FLNA
Active Antenna
LNA
Active Antenna
LNA
VANT