LG MG210, Service Manual, Page: 16 / 127

3. H/W Circuit Description
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3.2.1. RF Front End
RF front end consists of Front End Module(FL400), quad band LNAs integrated in transceiver(U400).
The Received RF signals (GSM-850 869MHz ~ 894MHz, EGSM 880 MHz ~ 960MHz, DCS 1710 MHz
~ 1880 MHz, PCS 1930MHz ~ 1990MHz) are fed into the antenna or mobile switch. An antenna
matching circuit is between the antenna and the mobile switch. The Front End Module(FL400) is used
for control the Rx and TX paths. And the input signals ANT_SW1 , ANT_SW2 and ANT_SW3 of a
FL400 are directly connected to baseband controller to switch either TX or RX path on.
Front End Module(FL400) is an antenna switch module for Quad band phone. The logic and current is
given below Table 3-2.
ADC
ADC
ADC
ADC
Di
gita
l Fi
lter
Di
gita
l Fi
lter
DAC
DAC
DAC
DAC
LOW
IF
LOW
IF
D
I
P
D
I
P
GSM
850
DCS
FL400
Front End Module
26MHz
I
Q
U400/Si4210
VCO + FREQUENCY
SYNTHESIZER
VCO + FREQUENCY
SYNTHESIZER
0 /
90
0 /
90
PGA PGA
X400
VC-TCXO
GSM
850
DCS
PCS
LNA
Baseband
(TI)
U101
(Calypso)
+
U100
(IOTA
Shrink)
Baseband
(TI)
U101
(Calypso)
+
U100
(IOTA
Shrink)
PCS
EGSM
EGSM
Figure 1. RF Receiver Block
Table 3-2. The Logic and Current
GSM900 Rx
DCS1800 Rx
GSM850 Rx
Tx 2GHz
Tx 1GHz
VC1 Switch Mode
PCS1900 Rx
VC2
VC3 VDD
H
H
L
L
L
L
L
H
H
H
L
L
L
L
H
L
H
L
H
H
H
H
H
H
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