3. TECHNICAL BRIEF
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Only for training and service purposes
LGE Internal Use Only
3.5.1.2 U1004, SKY77705-15
The SKY77705 Power Amplifier Module (PAM) is a fully matched 10-pad surface mount module developed for
Wideband Code Division Multiple Access (WCDMA) applications. This small and efficient module packs full
880–915 MHz bandwidth coverage into a single compact package. Because of high efficiencies attained
throughout the entire power range, the SKY77705 delivers unsurpassed talk-time advantages. The SKY77705
meets the stringent spectral linearity requirements of High Speed Downlink Packet Access (HSDPA), High Speed
Uplink Packet Access (HSUPA), and Long Term Evolution (LTE) data transmission with high power added
efficiency. 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-ohm load is realized off-chip within the module package to optimize efficiency and
power performance.
The SKY77705 PAM is manufactured with Skyworks’ InGaP GaAs Heterojunction Bipolar Transistor (HBT) BiFET
process that provides for all positive voltage DC supply operation while maintaining high efficiency and good
linearity. Primary bias to the SKY77705 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. No VREF voltage is required. Power down is
accomplished by setting the voltage on VENABLE 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.
[Figure 3.5.1.2] SKY77705 Block Diagram
Driver Stage
Bias
MMIC
MODULE
VEN (5)
VMODE_0 (4)
VMODE_1 (3)
VCC2 (10)
VCC1 (1)
RF_IN (2)
GND (7)
CPL_OUT (6)
CPL_IN (8)
Power Stage
Bias
Input Match
DA
Inter-Stage
Match
PA
Output
Match
(9) RF_OUT