DATA SHEET
SKY77500 iPAC™ FEM for Quad-Band GSM / GPRS
Applications
•
Quad-band cellular
handsets comprised of
-
Class 4 GSM850/900
-
Class 1 DCS1800
PCS1900
-
Class 12 GPRS multi-slot
operation
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.
Band selection and control of transmit and receive RF signal flows are performed by use of three
external control pins. See
Figure 1
shown below. Two band select pins select GSM, DCS or PCS
modes of operation and the TX_RX pin selects the receive or transmit mode of the respective RF
switch (TX = logic 1). Proper timing of the logic on this pin, PAC Enable, and Analog Power Control
(APC) allow for high isolation between the antenna and TX-VCO while the VCO is being tuned prior to
the transmit burst. The PAC Enable input allows initial turn-on of the PAC circuitry to minimize battery
drain.
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
Figure 1. Functional Block Diagram
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
103146A • Skyworks Proprietary information. • Products and product information are subject to change without notice. • May 16, 2005
1
SKYWORKS [ SKYWORKS SOLUTIONS INC. ]
