GNSS Module Series
L76&L76-L_Hardware_Design 39 / 59
The components C2, R1 and C3 are reserved for matching antenna impedance. By default, R1 is 0
Ω,
while C2 and C3 are not mounted; C1 is 100 pF; D1 is an electrostatic discharge (ESD) protection device
to protect the RF signal input from the potential damage caused by ESD.
An active antenna can use the power supply from the VDD_RF pin. In that case, the inductor L1 is used to
prevent the RF signal from leaking into the VDD_RF and to prevent noise propagation from the VDD_RF
to the antenna. The L1 inductor routes the bias voltage to the active antenna without losses. The
recommended value of L1 is no less than 47 nH. The resistor R2 is used to protect the modules in case
the active antenna is short-circuited to the ground plane.
The existing footprints in the matching circuit can be used to mount other type of components than the
ones presented in the figure above. In that case, you must pay attention to the DC power supply. For
example, if an inductor is mounted on the C1 footprint, then the circuit needs a DC-blocking capacitor
between L1 and C1 to prevent short-circuiting of the DC power supply through the inductor to the ground.
The same applies to the C2 footprint.
5.2.3.2. Active Antenna Reference Design with ANTON
All the modules can also reduce power consumption by controlling the power supply of active antenna
through the ANTON pin.
The reference circuit for active antenna with ANTON function is given as below.
VDD_RF
ANTON
Active Antenna
L
1
4
7
nH
R1
R2
10K
Q1
Q2
RF_IN
C1 NM
C2 NM
0R
π
Matching Circuit
10R
R3
Power Control Circuit
Module
TVS
D1
C
4
1
0
0
pF
C
5
1
0
0
nF
Figure 20: Reference Design for Active Antenna with ANTON
