Only For Training And Service Purposes - LG CT815 Service Manual

3.6.3 W-CDMA 2100 POWER AMPLIFIER (U108: SKY77170)
The SKY77170 Power Amplifier Module (PAM) is a fully matched 10-pad surface mount module
developed for Wideband Code Division Multiple Access (WCDMA) handsets. This small and efficient
module packs full 1920-1980 MHz bandwidth coverage into a single compact package. The SKY77170
meets the stringent spectral linearity requirements of High Speed Downlink Packet Access (HSDPA)
data transmission with high power added efficiency for power output of up to 27 dBm. A directional
coupler is integrated into the module thus eliminating the need for any external coupler.
The single Gallium Arsenide (GaAs) Microwave Monolithic Integrated Circuit (MMIC) contains all active
circuitry in the module. The MMIC contains on-board bias circuitry, as well as input and interstage
matching circuits. Output match into a 50-Ω load is realized off-chip within the module package to
optimize efficiency and power performance.
The SKY77170 PAM is 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 SKY77170 is supplied directly from any three-cell Ni-Cd, a single-cell
Li-Ion, or other suitable battery with an output in the 3.2 to 4.2 volt range. Power down is accomplished
by setting the voltage on the low current reference pad to zero volts. No external supply side switch is
needed as typical "off" leakage is a few microamperes with full primary voltage supplied from the
battery.
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Only for training and service purposes

[Figure 3.8] SKY77170 Functional Block Diagram.
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3. TECHNICAL BRIEF
LGE Internal Use Only