LG PRADA KE850 - Front End Module Control

3. TECHNICAL BRIEF
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3.26. Front End Module control
Implemented in the S-Gold2 (U101) are three outputs which are VC2, VC3 and VC4 for direct control
of front end modules with three logic input pins to select RX and TX mode as well as low and high
band operation.
Table 12 FEM Control Logic
Figure 40 FEM schematic
MODE Tx 1GHz Tx 2GHz Rx GSM Rx EGSM Rx DCS TX PCS
VDD ON ON ON ON ON ON
VCTRL1 ON ON OFF OFF OFF OFF
VCTRL2 OFF ON ON ON OFF OFF
VCTRL3 OFF OFF ON OFF ON OFF
GSM850
DCS
LB RF Input
Front End Module
EGSM
PCS
HB RF Input
0.1u
C405
VRF2V85
1.2p
C418
1.5p
C416
0
R403
1.5p
C417
1.2p
C419
L407
6
TX1G
8
TX2G
22
VCTRL1
VCTRL2
21
VCTRL3
20
VDD
3
EGSM_RX-
16
GMS_RX-
18
GND1
2
GND10
25 26
GND11
GND2
4
5
GND3
GND4
7
9
GND5
GND6
10
GND7
11 23
GND8 GND9
24
19
GSM_RX+
13
PCS_RX+
PCS_RX-
12
U401
YGHF-S006A
ANT
1
15
DCS_RX+
DCS_RX-
14
17
EGSM_RX+
L406
C467
100p
R436 100
R438 0
100R437
100p
C464
100R435
100p
C465
NA
C466
VC4
VC2
VC3
VC1