LG MG180C Service Manual page 16

FL500
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(FL500), quad band LNAs integrated in transceiver(U502).
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(FL500) is used for control the Rx and TX paths. And the input signals ANT_SW1 and
ANT_SW2 of a FL500 are directly connected to baseband controller to switch either TX or RX path on.
Front End Module(FL500) is an antenna switch module for Quad band phone. The logic and current is
given below Table 3-2.
GSM 850/EGSM RX
DCS/PCS RX
GSM-850/EGSM TX
DCS/PCS TX
LNA
GSM
850 PGA
EGSM
DCS
PCS
0 /
0 / VCO + FREQUENCY
VCO + FREQUENCY
90 SYNTHESIZER
90
SYNTHESIZER
Figure 1. RF Receiver Block
ANT_SW1(PIN 15)
0 V
2.5~3.0 V
0 V
2.5~3.0 V
Table 3-2. The Logic and Current
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3. H/W Circuit Description
LOW
LOW
IF
IF
PGA
ADC
ADC
ADC
ADC
ANT_SW1 2(PIN 14)
0 V
0 V
2.5~3.0 V
2.5~3.0 V
U502/Si4210
DAC I
Baseband
DAC
Baseband
(TI)
(TI)
U100
U100
Q
DAC
DAC
(Calypso +)
(Calypso +)
+
+
U100
U100
X501
(IOTA)
(IOTA)
VC-TCXO
26MHz
Current
< 0.1 mA
< 0.1 mA
< 0.1 mA
< 0.1 mA