LG CG225 Service Manual page 16

FL501
Front End Module
GSM
850
EGSM
DCS
PCS
D
D
I
I
P
P
3.2.1. RF Front End
Digital Filter Digital Filter
RF front end consists of Front End Module(FL501), 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(FL501) is used
for control the Rx and TX paths. And the input signals ANT_SW1 and ANT_SW2 of a FL501 are
directly connected to baseband controller to switch either TX or RX path on. Front End Module(FL501)
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
VC1(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
U502/Si4210
LOW
LOW
IF
IF
PGA
ADC
ADC
ADC
ADC
26MHz
VC2(PIN 14)
0 V
0 V
2.5~3.0 V
2.5~3.0 V
DAC I
Baseband
DAC
Baseband
(TI)
(TI)
U102
U102
Q
DAC
DAC
(Calypso +)
(Calypso +)
+
+
U101
U101
X501
(IOTA)
(IOTA)
VC-TCXO
Current
< 0.1 mA
< 0.1 mA
< 0.1 mA
< 0.1 mA