L10 Hardware Design
4.2.2 Active antenna
Active antenna has an integrated low-noise amplifier which could be connected to RF_IN directly. If an
active antenna is connected to RF_IN, the integrated low-noise amplifier of the antenna needs to be
supplied with the correct voltage through pin V_ANT. Usually, the supply voltage is fed to the antenna
through the coaxial RF cable. An active antenna consumes current at 5~20mA. The inductor inside the
module can separate the RF signal from the V_ANT pin and routes the bias supply to the active antenna.
The block diagram of the supply part for active antenna is shown in Figure 13.
Figure
13:
Active
antenna
biasing
If the active antenna is short-circuited, the module would turn off the power supply to the antenna
immediately. Afterwards, the antenna status will be detected every 60 seconds. When the short-circuit
problem is removed, it will recover the power supply to the active antenna.
If the VCC_RF voltage is suitable for powering the active antenna, pin VCC_RF could be directly
connected to pin V_ANT. A reference circuit is shown in Figure 14.
Figure
14:
Active
antenna
with
VCC_RF
If the VCC_RF voltage doesn’t meet the requirement for powering the active antenna, an external LDO
could be used. The output of the external LDO can be connected to pin V_ANT. A reference circuit is
shown in Figure 15.
L10_HD_V1.01
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