UC-00-M31 EN P1.0.0
Hardware Design
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3
Hardware Design
3.1
Antenna Feed Design
UM982 supports feeding the antenna both from the inside and outside of the module.
However, in order to effectively protect the module from lightning strike and surge, it is
strongly recommended to feed from the outside.
When feeding the antenna from the outside, you can use devices with high power and
that can withstand high voltage. Gas discharge tube, varistor, TVS tube and other high-
power protective devices may also be used in the power supply circuit to improve the
protection.
UM982
ANT1_IN
ANT1_BIAS
ANT1
ANT1_PWR
GND
L1
C2
C1
ANT2_PWR
ANT2_IN
L2
ANT2_BIAS
ANT2
C3
C4
D1
D3
D2
D4
Figure 3-1 UM982 External Antenna Feed Reference Circuit
Notes:
L1 and L2: feed inductor, 68 nH RF inductor in 0603 package is recommended
C1and C3: decoupling capacitor, recommended to connect two capacitors of
100 nF/100 pF in parallel
C2 and C4: DC blocking capacitor, recommended 100 pF capacitor
D1and D4: ESD diode, choose the ESD protection device that supports high frequency
signals (above 1000 MHz)
D2 and D3: TVS diode, choose the TVS diode with appropriate clamping specification
according to the requirement of feed voltage and antenna voltage
