PRODUCT SUMMARY
SKY77546 Tx–Rx Front-End Module for Dual-Band
GSM / GPRS / EDGE
Applications
•
Dual-band cellular handsets
encompassing
-
Class 4 GSM900
-
DCS1800
-
Class 12 GPRS multi-slot
operation
-
Linear EDGE operation
Description
The SKY77546 is a transmit and receive Front-End Module (FEM) designed in a compact form factor
for dual-band cellular handsets comprising GSM900 and DCS1800 operation. The SKY77546 offers a
complete Transmit VCO-to-Antenna and Antenna-to-Receive SAW filter solution that supports Class
12 General Packet Radio Service (GPRS) multi-slot operation and EDGE operation for handsets and
modules.
The module consists of a GSM900 PA block and a DCS1800 PA block, impedance-matching circuitry
for 50
Ω
input and output impedances, TX harmonics filtering, high linearity and low insertion loss RF
switches, and a Power Amplifier Control (PAC) block. A custom CMOS integrated circuit provides the
internal PAC function, external interface circuitry, and decoder circuitry to control the RF switches.
The integrated PAC function provides envelope amplitude control by reducing sensitivity to input drive,
temperature, power supply, and process variations. The Heterojunction Bipolar Transistor (HBT) PA
blocks are fabricated onto a single InGaP/GaAs die. One PA block supports the GSM900 band and the
other PA block supports the DCS1800 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 a diplexer and SP2T switch. The GaAs die, switch 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 RF signal flows are performed using five external
control pads. The band select pad (BS) selects GSM or DCS modes of operation. The TxEN pad selects
receive or transmit mode of the respective RF switch (Tx = logic 1). SW_EN provides improved
isolation for flexibility in control timing to meet the required time mask. MODE configures the
amplifier for GMSK operation (MODE = 0) or linear EDGE operation (MODE = 1). Proper timing of the
logic on these pads, and Analog Power Control (APC) allows for high isolation between the antenna
and Tx-VCO while the VCO is being tuned prior to the transmit burst. Standby mode provides a low-
current consumption state. Low leakage current (6.5 μA, typical) of the dual PA module maximizes
handset standby time.
Features
•
High efficiency
45% (GSM900)
40% (DCS1800)
•
Current limiting for
protection and extended
battery life
•
Input/Output internally
matched 50
Ω
•
TX–VCO-to-antenna and
antenna-to-RX-SAW filter
RF interface
•
TX harmonics below
–36 dBm
•
Small, low profile package
-
7 mm x 6 mm x 0.9 mm
-
30-pad configuration
•
Low APC current: 15 μA
Figure 1. Functional Block Diagram
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201052B • Skyworks Proprietary and Confidential Information • Products and Product Information are Subject to Change Without Notice. • July 2, 2009
1
SKYWORKS [ SKYWORKS SOLUTIONS INC. ]
