LG KF690 Service Manual page 21

3. TECHNICAL BRIEF
3.4.4 GSM PAM (U101: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 ߟ 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.
C133
56p
L113
1.5nH
L114
16
8.2nH
DCS_PCS_OUT
9
GSM_OUT
R109
0
C135
82p
L115
NA
LGE Internal Use Only
C134 C127
100p 22u
tcc_16085h_9_r
2
DCS_PCS_IN
7
U101 GSM_IN
SKY77329
1
TX_EN
3
BS
GSM_PA_BAND
C141 C142
1000p 1000p
[Fig. 3.5] GSM PAM Schematic
- 22 -
2.2K R105
GSM_PA_RAMP
+VPWR
C132
68p
R106
68
R107 R108
FL101
10 dB
91 91
EFCH897MTDB1
3 2
R111
G2 G1
IN
1
O1 G3
51
4 5
R112 R113
8 dB
120 120
GSM_PA_EN
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
DCS_PCS_TX
GSM_TX