DATA SHEET
SKY77517–21 TX-RX iPAC™ FEM for Dual-Band GSM/GPRS
Applications
• Dual-band cellular handsets
encompassing
- Class 4 GSM850
- PCS1900
- Class 12 GPRS multi-slot
www.DataSheet4Uo.pceormation
Features
• High efficiency
- GSM850 48%
- PCS 41%
• Low transmit supply current
- GSM850 1.26 A
- PCS1900 0.9 A
• Internal ICC sense resistor for iPAC
• Closed loop iPAC
• 50 Ω matched Input/Output
• 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: 6 mm x 8 mm
• Low profile: 1.2 mm
• Compatible with multiple logic
families
• Low APC current: 25 μA
Description
The SKY77517–21 is a transmit and receive front-end module (FEM) with Integrated Power
Amplifier Control (iPAC™) for dual-band cellular handsets comprising GSM850 and PCS1900
operation. Designed in a low profile, compact form factor, the SKY77517–21 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 PA block and a PCS1900 PA block, impedance-matching
circuitry for 50 Ω 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. One PA
block supports the GSM850 band and the other PA block supports the PCS1900 band. Both PA
blocks share common power supply pads to distribute current. The output of each PA block
and the outputs to the two receive pads are connected to the antenna pad through PHEMT RF
switches and a diplexer. The GaAs die, PHEMT die, Silicon (Si) die and passive components are
mounted on a multi-layer laminate substrate. The assembly is encapsulated with plastic
overmold.
Band selection and control of transmit and receive modes are performed using two external
control pads. Refer to the functional block diagram in Figure 1 below. The band select pad (BS)
selects between GSM and PCS modes of operation. The transmit enable (TX_EN) pad controls
receive or transmit mode of the respective RF switch (TX = logic 1). Proper timing between
transmit enable (TX_EN) and Analog Power Control (VRAMP) allows for high isolation between
the antenna and TX-VCO while the VCO is being tuned prior to the transmit burst.
The SKY77517 is compatible with logic levels from 1.2 V to VCC for BS and TX_EN pads,
depending on the level applied to the VLOGIC pad. This feature provides additional flexibility for
the designer in the selection of FEM interface control logic.
Figure 1. Functional Block Diagram
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
200784A • Skyworks Proprietary and Confidential Information • Products and Product Information are Subject to Change Without Notice. • November 6, 2007
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