SKY77534 Datasheet, PDF (1/2 Pages) Skyworks Solutions Inc. – Internal ICC sense resistor for iPAC

PRODUCT SUMMARY
SKY77534 Tx–Rx iPAC^™ FEM — Dual–Band GSM/GPRS
Applications
• Dual-band cellular handsets
encompassing
- Class 4 GSM850/900
- DCS1800/PCS1900
- Class 12 GPRS multi-slot
operation
Features
• High efficiency
- 44% (GSM850/900)
- 42% (DCS1800/PCS1900)
• Low transmit supply current
- 1.30 A (GSM850/900)
- 0.86 A
(DCS1800/PCS1900)
• 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 switch affords
high linearity, low insertion
loss, and less than 20 μA
supply current in receive
modes
• Small outline:
6 mm x 8 mm
• Low profile: 1.05 mm
• Compatible with multiple
logic families
• Low APC current: 25 μA
Description
SKY77534 is a transmit and receive front-end module (FEM) with Integrated Power Amplifier Control
(iPAC^™) for Dual-band cellular handsets comprising GSM850/900 and DCS1800/PCS1900 operation.
Designed in a low profile, compact form factor, the SKY77534 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 ohm 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 Heterojunction 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. Both PA blocks share common power
supply pads to distribute current. The output of each PA block and the outputs to the four receive
pads are connected to the antenna pad through a PHEMT RF switch. 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 are performed using four external control pads.
Refer to the block diagram in Figure 1 below. The band select pads, BS1 and BS2, select GSM850,
GSM900, DCS, and PCS modes of operation. Transmit enable Tx_EN controls receive or transmit
mode of the 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 SKY77534 is compatible with logic levels from 1.2 V to VCC for BS1, BS2, 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. SKY77534 Functional Block Diagram
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
200900A • Skyworks Proprietary and Confidential Information • Products and Product Information are Subject to Change Without Notice. • May 12, 2008
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