Front End Module Control; Power Amplifier Module - LG KE820 Service Manual

3.25. Front End Module control

Implemented in the S-Gold2 (U102) are three outputs which are ANT_SW1, ANT_SW2 and ANT_SW3
for direct control of front end modules with three logic input pins to select RX and TX mode as well as
low and high band operation.
MODE Tx 1GHz
VDD ON
VCTRL1 ON
VCTRL2 OFF
VCTRL3 OFF
2V85_RF
C437
0.1u
GND11
26
GND10
25
ANT GND9
1 24
GND8
23
GND7
11

3.26. Power Amplifier Module

The RF3158 (U401) is a high-power, dual-mode amplifier (PA) with integrated power control. This PA
is designed to operate both in a saturated mode for GMSK signaling and in a linear mode for 8PSK
modulation. Featuring input and output terminals that are internally matched to 50 ohms, the PAM is
designed to be the final amplification stage in a dual-mode GSM/EDGE mobile transmit lineup
operating in the 824 MHz to 915 MHz (low) and 1710 MHz to 1910 MHz (high) bands.
Tx 2GHz Rx GSM
ON ON
ON OFF
ON ON
OFF ON
NA NA
C410 C411
L407
3.9nH
R408
0
L406
C412
10nH
NA
Figure 41 FEM schematic
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3. TECHNICAL BRIEF
Rx EGSM Rx DCS
ON ON
OFF OFF
ON OFF
OFF ON
R403 100
R405 100
R441 100
C454 C453 C452
100p 100p 100p
VSUPPLY
NC3 LB_RFIN
20 7
NC2 U401 VRAMP
15 6
NC1 VMODE
RF3158
10 5
VBATT
4
LB_RFOUT TX_EN
12 3
BAND_SEL
2
HB_RFOUT HB_RFIN
18 1
TX PCS
ON
OFF
OFF
OFF
ANT_SW1
ANT_SW2
ANT_SW3
C401 C402 C409 C
100p 100p 100p 10
C408 C414