LG -T370 Service Manual page 39

3.5.2.3 Front-end/PA Control Interface
Two outputs (FE1, FE2) for direct control of antenna switch modules enable to select RX- and TX-mode as well
as low- and high-band operation.
An extra band select signal PABS for the power amplifier is used, to support discrete PA and switching
modules. Time accurate power dissipation of the PA is achieved by the control signal PAEN.
A minor set of power amplifiers require a bias voltage to enhance power efficiency. Support of this power
amplifiers is achieved by the implemented bias DAC. amplifiers is achieved by the implemented bias DAC
biasdac_data
to
baseband
as rf_fe4_0
FE4
LGE Internal Use Only LGE Internal Use Only
INIT_PAFEM_A
PABIASFE 3_SEL
BIAS
DAC
FE3
PAEN
CHANNEL_BSW[1]
INIT_PAFEM_A.PABS_INV
ramping signal
FE2
FE1
Figure. 3.5.4 PA AND FEM CONTROL BLOCK DIAGRAM Fi 3 5 4 PA AND FEM CONTROL BLOCK DIAGRAM
TX2
RFIN
GSM 1800/1900
HB
GMSK PA
TX1 RFIN
GSM 850/900
LB
PABIAS/FE3
PAEN
PABS
VPAMP
PAMP
DAC
FE2
FE1
- 39 - - 39 - Copyright © 011 LG Electronics. Inc. All right reserved. Copyright © 01 LG Electronics. Inc. All right reserved.
3. TECHNICAL BRIEF
3. TECHNICAL BRIEF
to ASM / FEM
RFOUT
HB
to ASM / FEM
RFOUT
LB
Only for training and service purposes Only for training and service purposes