LG F1200 Service Manual page 18

(3) Power Amplifier Module
The SKY77325[U100] is a triple-band GSM/DCS/PCS power amplifier module that incorporates
an indirect closed loop method of power control. The indirect closed loop is fully self-contained
and it does not require loop optimization. It can be driven directly from the DAC output in the
baseband circuit. On-board power control provides typical 50 dB of control range with an analog
voltage input (Vapc). Efficiency is 53% at GSM, DCS and PCS.
(4) Power Supplies and Control Signals
An external regulator (U104) is used to provide DC power to RF part. Every RF component
except power amp module uses this external regulator.
RF2.85V
MIC5255-2.85BM5
C133
1u
Figure 5. POWER AMP
VBAT
U104
5 1
OUT IN
2
GND
4 3
BYP EN
C132 C131
0.01u 2.2u
Figure 6. POWER SUPPLY & CONTROL
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3. TECHNICAL BRIEF
RF_EN
C130
1000p