Description
The SKY77500 is a transmit and receive Front End Module (FEM) designed in a low profile (1.2 mm), compact form factor for quad-band cellular handsets comprising GSM850/900, DCS1800, and PCS1900 operation—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 separate GSM850/900 and DCS1800/PCS1900 PA blocks, internal circuitry for matching to 50 Ω input and output impedances, TX harmonics filtering, high linearity and low insertion loss PHEMT RF switches, diplexer, and an integrated power amplifier control (iPAC™) function that utilizes an internal current-sense resistor. A custom silicon integrated circuit contains decoder circuitry to control the RF switches while providing a low current external control interface.
Two Heterojunction Bipolar Transistor (HBT) PA blocks are fabricated onto a single Gallium Arsenide (GaAs) die; one 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 output of each PA block and the outputs to the four receive pins are connected to the antenna pin through PHEMT RF switches and a diplexer. The GaAs die, PHEMT dies, Silicon (Si) die, and passive components are mounted on a multi-layer laminate substrate. The assembly is encapsulated with plastic overmold.

FEATUREs
• High efficiency
   - GSM850 43%
   - GSM900 43%
   - DCS 40%
   - PCS 40%
• Internal ICC sense-resistor for iPAC
• Closed loop iPAC or open
   loop operation with external PAC circuit
• Input/Output matching 50
   ohms internal (with DC blocking)
• TX-VCO-to-antenna and
   antenna-to-RX-SAW filter RF interface
• TX harmonics below
   –33 dBm·
• PHEMT RF switches afford
   high linearity, low insertion
   loss and less than 20 µA
   supply current in receive modes
• Small outline
   - 8 mm x 10 mm
• Low profile
   - 1.2 mm maximum
• Low APC current:
   - 20 µA
• Gold plated, lead free contacts
• High impedance control
   inputs, 15 µA, typical

APPLICATIONs
• Quad-band cellular handsets comprised of
   - Class 4 GSM850/900
   - Class 1 DCS1800 PCS1900
   - Class 12 GPRS multi-slot operation