Front End Module Control - LG KF350 Service Manual

3. TECHNICAL BRIEF

3.21 Front End Module control

Implemented in the S-Gold3 (FL400) are two outputs which are FE1, FE2 for direct control of front end
modules with two logic input pins to select RX and TX mode as well as low and high band operation.
FEM need 2V85_VRF supply.
MODE
VDD
VC1
VC2
VC1 (FE1) VC2 (FE2)
GSM850 / 900_TX H H
GSM 1800 / 1900_ TX L H
GSM850 / 900_RX H L
GSM 1800 / 1900_ RX L L
ANT400
WFL-R-SMT10
G1
SW400
G2
G3 ANT
LGE Internal Use Only
Tx 1GHz
ON
ON
ON
2V85_VRF
C400
1000p
C406
RF-800 LMSP43QA-538
100p
G2
ANT
ANT RF
G1 11
L406
C407
100nH
DNI
Figure 29 FEM schematic
Tx 2GHz Rx 1GHz
ON ON
OFF ON
ON OFF
LMSP43QA-538(CMOS)
C401
100p
NC2
FL400
24
NC1
23
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Rx 2GHz
ON
OFF
OFF
R402
100ohm
FE1
FE2
R403
100ohm
C402
100p
L404
6.8nH
C411
C410
0.5p
0.5p
Only for training and service purposes