LG KF310 Service Manual page 24

3.5.5 GSM PAM (U1001:SKY77329)
The SKY77329 Power Amplifier Module (PAM) is designed in a compact form factor for quad-band
cellular handsets comprising GSM850/900, DCS1800, PCS1900, and supports Class 12 General
Packet Radio Service (GPRS) multi-slot operation. The module consists of a GSM850/900 PA block
and a DCS1800/PCS1900 PA block, impedance matching circuitry for 50 Ω input and output
impedances, and a Power Amplifier Control (PAC) block. A custom CMOS integrated circuit provides
the internal PAC function and interface circuitry. Two separate Hetero-junction Bipolar Transistor
(HBT) PA blocks are fabricated onto InGaP/GaAs die; one supports the GSM850/900 bands, the other
supports the DCS1800 and PCS1900 bands. Both PA blocks share common power supply pins to
distribute current. The GaAs die, the silicon die, and the passive components are mounted on a multi-
layer laminate substrate and the entire assembly is encapsulated with plastic overmold.
+VPWR
C1068
R1020 0
3.9p
C1069
3.3nH
L1008 C1074
1.8nH
39p
C1075
15nH
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
C1059 C1060 C1063
33u 15p
1000p
DCS_PCS_IN
16
DCS_PCS_OUT U1001 GSM_IN
SKY77329
9
GSM_OUT TX_EN
BS
[Figure 3.5.5] GSM PAM Schematic
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3. TECHNICAL BRIEF
R1018
2.2K
C1062
39p
2
7
1
3
GSM_PA_RAMP
GSM_PA_BAND
GSM_PA_EN
GSM_PA_BAND MODE
LOW GSM
HIGH DCS/PCS
GSM_PA_EN PA STATE
TX_DCS_PCS
LOW OFF
HIGH ON
TX_GSM
LGE Internal Use Only