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FL801
Antenna Switch
EGSM
DCS
PCS
D
D
I
I
P
P
3.2.1. RF Front End
RF front end consists of Antenna Switch(FL801), triple band LNAs integrated in transceiver(U803).
The Received RF signals (EGSM 925MHz ~ 960MHz, DCS 1805MHz ~ 1880MHz, PCS 1930MHz ~
1990MHz) are fed into the antenna or mobile switch. An antenna matching circuit is between the
antenna and the mobile switch. The Antenna Switch(FL801) is used for control the Rx and TX paths.
And the input signals VC1,VC2 and VC3 of a FL801 pass through triple-buffer(U801) are directly
connected to baseband controller to switch either TX or RX path on. Ant S/W (FL801) is an antenna
switch module for triple band phone. The logic and current is given below Table 3-1.
EGSM RX
DCS RX
PCS RX
EGSM TX
DCS/PCS TX
Figure 1. RF Receiver Block
LNA
GSM
DCS
PCS
÷2:GSM
0˚/
÷2:GSM
0˚/
90˚
90˚
÷1:DCS
÷1:DCS
Table 3-1. The Logic and Current
VC1
0 V
0 V
2.5~3.0 V
0 V
0 V
2.5~3.0 V
100KHz
100KHz
PGA
ADC
ADC
ADC
ADC
RF1
RF
RF
PLL
PLL
RF2
VC2
VC3
0 V
0 V
0 V
0 V
0 V
0 V
0 V
2.5~3.0 V
0 V
-13-
U803/Si4205
PGA
DAC
I
Baseband
DAC
Baseband
(TI)
(TI)
U102
U102
Q
DAC
DAC
(Calypso)
(Calypso)
U101
U101
X801
(IOTA)
(IOTA)
VC-TCXO
26MHz
Current
< 0.1 mA
< 0.1 mA
10.0 mA max
10.0 mA max
10.0 mA max
+
+
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