LG L601i Service Manual page 29

3. TECHNICAL BRIEF
Figure 3.5.5-1 Block diagram of LMV225TLX Typical Application
Figure 3.5.5-2 Power detector response, Vout vs PA output power
3.5.6 Dual band GSM power amplifier (U102)
The SKY77328 Power Amplifier Module (PAM) is designed in a low profile (1.2mm), 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 GSM850/900 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 GSM850/900 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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