Power Amplifier Module (Sky77318) - LG KG270 Service Manual

3. TECHNICAL BRIEF

3.2 Power Amplifier Module (SKY77318)

Figure. 3-2 SKY77318 FUNCTIONAL BLOCK DIAGRAM
The SKY77318 Power Amplifier Module (PAM) is designed in a low profile (1.2 mm), compact form
factor for quad-band cellular handsets comprising GSM850/900, DCS1800, and PCS1900 operation.
The PAM also supports Class 12 General Packet Radio Service (GPRS) multi-slot operation.
The module consists of separate GSM PA and DCS1800/PCS1900 PA blocks, impedance-matching
circuitry for 50 Ω input and output impedances and a Power Amplifier Control (PAC) block with an
internal current-sense resistor. The custom BiCMOS integrated circuit provides the internal PAC
function and interface circuitry.
Fabricated onto a single Gallium Arsenide (GaAs) die, one Heterojunction Bipolar Transistor (HBT) PA
block supports the GSM bands and the other supports the DCS1800 and PCS1900 bands. Both PA
blocks share common power supply pins to distribute current.
The GaAs die, the Silicon (Si) die, and the passive components are mounted on a multi-layer laminate
substrate. The assembly is encapsulated with plastic overmold.
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