Fem With Integrated Power Amplifier Module; General Description - LG GX300 Service Manual
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- User manual (106 pages)
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3.4 FEM with integrated Power Amplifier Module
(SKY77547, U300, U302)
3.4.1 Internal Block Diagram
3.4.2 General Description
The SKY77547 is a transmit and receive front-end module (FEM) with Integrated Power Amplifier Control
for quad-band cellular handsets comprising GSM850/900 and DCS1800/PCS1900 operation. Designed in
a low profile, compact form factor.
The FEM also 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
input and output impedances, TX harmonics filtering, high linearity and a low insertion
loss PHEMT RF switch, and a Power Amplifier Control (PAC) block with internal current sense resistor. A
custom BiCMOS integrated circuit provides the internal PAC function and decoder circuitry to control the
RF switches. The two Heterojunction Bipolar Transistor (HBT) PA blocks are fabricated onto a single
Gallium Arsenide (GaAs) die. One PA block supports the GSM850/900 bands and the other PA block
supports the DCS1800/PCS1900 bands. Both PA blocks share common power supply pads to distribute
current. The output of each PA block and the outputs to the four receive pads are connected to the
antenna pad through a PHEMT RF switch. The GaAs die, PHEMT die, Silicon (Si) die and passive
components are mounted on a multi-layer laminate substrate. The assembly is encapsulated with plastic
overmold.
Copyright © 2010 LG Electronics. Inc. All right reserved.
Only for training and service purposes
Figure. 3.4.1 SKY77547 FUNCTIONAL BLOCK DIAGRAM
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3. TECHNICAL BRIEF
3. TECHNICAL BRIEF
LGE Internal Use Only
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