
LGE Internal Use Only
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
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.
3. TECHNICAL BRIEF
- 30 -
[Figure 1. 8] GSM PAM Schematic
8.5dB
13dB
MODE
GSM
LOW
GSM_PA_BAND
EGSM
HIGH
DCS/PCS
R108
15K
C142
91
R111
68p
100p
C150
100p
C154
33p
C131
L110
10nH
6
VCC1B
EGSM_OUT
11
ENABLE
18
GND1
5
GND2
7
8
GND3
9
GND4
10
GND5
GND6
12
GND7
13
GND8
14
GND9
16
21
P_GND
19
RSVD_GND
VAPC
20
17
VBATT
2
VCC1A
SKY77318
U102
BS
1
DCS_PCS_IN
3
15
DCS_PCS_OUT
EGSM_IN
4
R109
120
C125
2p
NA
L124
L107
15nH
100ohm
R115
2
G1
3
G2
5
G3
1
IN
4
O1
51
R113
EFCH897MTDB1
FL100
0.01u
C141
C127
0.01u
91
R110
0.01u
C140
15nH
L104
R116
100ohm
33p
C130
L109
NA
33u
C126
+VPWR
GSM_PA_RAMP
GSM_PA_EN
GSM_PA_BAND
DCS_PCS_TX
GSM_TX
Summary of Contents for U370
Page 1: ...Date January 2008 Issue 1 0 Service Manual Model U370 Service Manual U370 ...
Page 178: ...Note ...
Page 179: ...Note ...