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LGE Internal Use Only
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
3. TECHNICAL BRIEF
The SKY77175 Power Amplifier Module (PAM) is a fully matched, 14-pad, surface mount module
developed for Wideband Code Division Multiple Access (WCDMA) applications. This small and efficient
module packs full WCDMA Band II and Band V coverage into a single compact package.
The SKY77175 meets the stringent spectral linearity requirements of WCDMA transmission, with high
power added efficiency for power output to 29 dBm (Band II) and 29 dBm (Band V). A low current
analog pad (VCONT) is provided to improve efficiency for the low RF power range of operation.
Gallium Arsenide (GaAs) Microwave Monolithic Integrated Circuits (MMIC) contain all active RF
circuitry as well as input and interstage matching circuits. Output match is realized off-chip within the
module package to optimize efficiency and power performance into a 50
Ω
load. The devices are
manufactured with Skyworks’ GaAs Heterojunction Bipolar Transistor (HBT) process that provides for
all positive voltage DC supply operation while maintaining high efficiency and good linearity. Primary
bias to the SKY77175 is supplied directly from a three-cell Ni-Cad, a single-cell Li-Ion, or other
suitable batteries with outputs in the 3.1 to 4.6 volt range. Power down is accomplished by setting a
logic low level on the VEN pad. No external supply side switch is needed as typical “off” leakage is 15
microamperes with full primary voltage supplied from the battery.
C. Power Amplifier Module
Figure 3-7-5. SKY77182 Functional Block Diagram
Figure 3-7-6. WCDMA PAM schematic
Rev. 1.1
Rev. F
68
R111
1.2p
C110
TP101
0.1u
C119
22p
C103
C113
22p
R112
68
5
VEN_BAND_2
1
7
VEN_BAND_5
SKY77175
U103
3
GND1
GND2
8
GND3
12
14
GND4
IN_BAND_2
2
6
IN_BAND_5
13
OUT_BAND_2
OUT_BAND_5
9
PGND
15
10
VBIAS
VC2
11
4
VCC1
VCONT
22p
C120
DAP
7
4
EN
GND
3
OUT
6
5
REF
2
RF_IN
VDD
1
U105
LMV221
C104
0.1u
LDC151G8820Q-359
U101
3
CO
U
IN
2
1
OUT
4
TER
L102
12p
200
R110
VDDA_2V8
R103
51
33nF
C123
OUT
1
4
TER
LDC15836M20Q-360
U104
3
COU
IN
2
1K
R108
1000p
C102
VBAT
1.5nH
L101
TP102
470p
C112
C108
22p
C118
DNI
C111
22p
8.2nH
C117
DNI
C109
WPOW_DET_EN
BIAS_CTRL
WPOW_DET
VCC_WPA
WTX_BAND_2_TO_PA
WTX_BAND_5_TO_PA
WTX_BAND_2_EN
WTX_BAND_5_EN