¡El 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. ¡El FEM also supports Class 12 General Packet Radio Service (GPRS) multi-slot operation. ¡El 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. ¡El 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. ¡El GaAs die, PHEMT dies, Silicon (Si) die, and passive components are mounted on a multi-layer laminate substrate. ¡El assembly is encapsulated with plastic overmold.