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Only for training and service purposes
3. TECHNICAL BRIEF
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3.3.1 Internal Block Diagram
3.3 FEM with integrated Power Amplifier Module (SKY77547, U303)
Figure. 3.3.1 SKY77547 FUNCTIONAL BLOCK DIAGRAM
3.3.2 General Description
The SKY77547 is a transmit and receive front-end module (FEM) with Integrated Power Amplifier
Control (iPAC™) for quad-band cellular handsets comprising GSM850/900 and DCS1800/PCS1900
operation. Designed in a low profile, compact form factor, the SKY77547 offers a complete
Transmit VCO-to-Antenna and Antenna-to-Receive SAW filter solution. The FEM also supports
Class 12 General Packet Radio Service (GPRS) multi-slot operation.
The module consists of a GSM850/900 PA block and a DCS1800/PCS1900 PA block, impedance
matching circuitry for 50
ȳ
input and output impedances, Tx harmonics filtering, high linearity
and a low insertion loss PHEMT RF switch, 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 Hetero junction Bipolar
Transistor (HBT) PA blocks are fabricated onto a single Gallium Arsenide (GaAs) die. One PA block
supports the GSM850/900 bands and the other PA block supports the DCS1800/PCS1900 bands.
3. TECHNICAL BRIEF
The SKY77547 is a transmit and receive front-end module (FEM) with Integrated Power Amplifier Control
(iPAC™) for quad-band cellular handsets comprising GSM850/900 and DCS1800/PCS1900 operation.
Designed in a low profile, compact form factor, the SKY77547 offers a complete Transmit VCO-to-Antenna
and Antenna-to-Receive SAW filter solution. The FEM also supports Class 12 General Packet Radio Service
(GPRS) multi-slot operation.
The module consists of a GSM850/900 PA block and a DCS1800/PCS1900 PA block, impedance matching
circuitry for 50 Ω input and output impedances, Tx harmonics filtering, high linearity and a low insertion
loss PHEMT RF switch, 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 Hetero junction Bipolar Transistor (HBT) PA blocks are fabricated onto a single
Gallium Arsenide (GaAs) die. One PA block supports the GSM850/900 bands and the other PA block
supports the DCS1800/PCS1900 bands.
