LG MG210 Service Manual page 16

FL400
Front End Module
GSM
850
EGSM
DCS
PCS
D
D
I
I
P
P
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.
Switch Mode
Tx 1GHz
Tx 2GHz
GSM850 Rx
GSM900 Rx
DCS1800 Rx
PCS1900 Rx
LNA
GSM
850 PGA
EGSM
DCS
PCS
0 /
0 /
VCO + FREQUENCY
VCO + FREQUENCY
90
SYNTHESIZER
90
SYNTHESIZER
Figure 1. RF Receiver Block
VC1 VC2
H L
H
H
L H
H
L
L L
L L
Table 3-2. The Logic and Current
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3. H/W Circuit Description
U400/Si4210
LOW
LOW
IF
IF
PGA
ADC
ADC
ADC
ADC
26MHz
VC3
L
L
H
L
H
L
Baseband
Baseband
DAC I
DAC
(TI)
(TI)
U101
U101
(Calypso)
Q (Calypso)
DAC
DAC
+
+
U100
U100
(IOTA
(IOTA
X400
Shrink)
Shrink)
VC-TCXO
VDD
H
H
H
H
H
H