Only For Training And Service Purposes - LG U370 Service Manual

3. TECHNICAL BRIEF
3.5.5 GSM PAM (U102 : SKY77318)
The SKY77318 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 Heterojunction 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.
L110
L109
10nH
NA
C130 C131
33p 33p
L124
NA
15
11
19
21
LGE Internal Use Only
+VPWR
C127 C126
33u
0.01u
C140
0.01u
C141
C142 0.01u
68p
3
DCS_PCS_OUT DCS_PCS_IN
4
EGSM_OUT U102 EGSM_IN
18
RSVD_GND ENABLE
SKY77318
1
P_GND BS
C154
100p
[Figure 1. 8] GSM PAM Schematic
L104 15nH
C125
EGSM
2p
L107 15nH
FL100
4 5
O1 G3
1
IN
G2 G1
3 2
GSM_PA_EN
C150
100p
EFCH897MTDB1
GSM_PA_BAND
GSM_PA_BAND
LOW
HIGH
Copyright © 2007 LG Electronics. Inc. All right reserved.
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13dB
R109
DCS_PCS_TX
120
8.5dB
R113
GSM_TX
51
MODE
GSM
DCS/PCS

Only for training and service purposes