SKY77521 Datasheet, PDF (1/2 Pages) Skyworks Solutions Inc. – Triple band WCDMA antenna switch support

PRODUCT SUMMARY
SKY77521 Tx-Rx FEM for Quad-Band GSM / GPRS / EDGE –
Triple-Band WCDMA Antenna Switch Support
Applications
• Quad-band cellular handsets
encompassing
- Class 4 GSM850/900
- Class 1 DCS1800 PCS1900
- Class 12 GPRS multi-slot
operation
- EDGE polar modulation
- Triple band WCDMA antenna
switch support
Features
• Small outline: 7 mm x 6 mm
• Very low profile: 1 mm max.
• 30-pad package
• Low input power range
- 0 to 6 dBm
• High efficiency
- GSM850 40%
- GSM900 40%
- DCS 34%
- PCS 34%
• TX-VCO-to-antenna and antenna-
to-RX-SAW filter RF interface
• Tx harmonics below -35 dBm
• Wideband envelop control path
• Input/Output matching 50 Ω
internal
• Low APC current: 20 μA
• High impedance control inputs
15 μA, typical
Description
SKY77521 is a transmit and receive Front End Module (FEM) designed in a very low profile
(1 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 and EDGE Polar Modulation. WCDMA switch-through support is
provided by three dedicated high-linearity ports.
The module consists of a GSM850/900 PA and DCS1800/PCS1900 PA block, impedance-
matching circuitry for 50 Ω input and output impedances, TX harmonic filtering, high linearity-
low insertion loss switches, and a CMOS Power Amplifier Control (PAC) block. A custom silicon
integrated circuit contains decoder circuitry to control the RF switch while providing a low
current external control interface.
Fabricated in InGaP/GaAs, the Heterojunction Bipolar Transistor (HBT) PA blocks support the
GSM850/900 bands and DCS1800/PCS1900 bands. Both PA blocks share common power
supply pads to distribute current. The output of the PA block and the outputs to the seven
receive pads connect to the antenna pad through a highly linear antenna switch. The
InGaP/GaAs die, switch die, Silicon (Si) controller die, and passive components are mounted on
a multi-layer laminate substrate and the entire assembly is encapsulated with plastic overmold.
RF input and output ports of the SKY77521 are internally matched to a 50 Ω load to reduce the
number of external components for a quad-band design. Extremely low leakage current
(10 μA, typical) of the FEM maximizes handset standby time. Band selection and control of
transmit and receive RF signal flows are performed by use of four external control pads. See
Figure 1 shown below. Mode of operation TX, RX, Band (GSM850, GSM900, DCS, PCS, and
UMTS) is controlled with 4 logic inputs: BS1, BS2, Mode, and Enable. Proper timing of the
TXEN input and the VAPC input ensures high isolation between the antenna and TX-VCO while
the VCO is being tuned prior to the transmit burst. The Enable input controls the initial turn-on
of the PAC circuitry to minimize battery drain.
The integrated power amplifier control (PAC) function provides envelope amplitude control by
reducing sensitivity to input drive, temperature, power supply, and process variation.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
200596A • Skyworks Proprietary and Confidential Information • Products and Product Information are Subject to Change Without Notice. • April 18, 2008
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