Power Amplifier Modul(Sky77518) - LG KP105 Service Manual

3. TECHNICAL BRIEF

3.2 Power Amplifier Modul(SKY77518)

Figure. 3-2 SKY77518 FUNCTIONAL BLOCK DIAGRAM
The SKY77518 is a transmit and receive front_end module(FEM) with integrated Power Amplifier
Control for dual_band cellular handsets comprising GSM900 and DCS 1800 Operation. Designed in a
low profile, compact form factor, the SKY77518 offers a complete transmit VCO-to Antenna and
Antenna-to-Receive SAW filter solution.
The module consists of a GSM900 PA block and a DCS1800 PA block, impedancematching circuitry
for 50ohm input and output impedances, Tx harmonics filtering, high linearity and low insertion loss
PHEMT RF switches, diplexer 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.
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