The SKY77455 Front-End Module (FEM) is a fully matched, 16-pad surface mount module
developed for LTE/EUTRAN applications. Small and efficient, this LTE FEM integrates the
interstage filter, input and output matching, power amplifier, power detection, and duplexer
into a single 4 x 7 x 1.1 mm package. The SKY77455 meets the stringent spectral
linearity requirements of LTE with QPSK/16QAM modulations from 1.4 to 20MHz bandwidth
and full or partial resource block allocations with high power added efficiency. The FEM
incorporates Inter-Stage Filter and Duplexer, InGaP BiFET PA, and output power detector.
Integration of the RF front-end greatly simplifies the design of the 4G-compatible handset
radio or data card as all critical matching between the interstage filter, PA, power detection,
and duplexer is optimized within the single module component. By optimizing the efficiency
of the InGaP BiFET PA MMIC, reducing RF loss between the integrated components and
within the Duplexer itself, and improving the match between the PA and the Duplexer, this
FEM achieves low current at maximum output power that significantly reduces the power
dissipated in the LTE-enabled handsets or data cards. Primary bias to the SKY77455 is
supplied via the VCC1 and VCC2 pads directly from a three-cell Ni-Cad, a single-cell Li-Ion,
or other suitable batteries with outputs in the 3.0 to 4.6 volt range, while the bias network is
powered up with the VCCB pad. DC-DC converter operation can be supported with lower
power operation down to 1.5V. Power down is accomplished by setting a logic low level on
the VEN pad. No external supply side switch is needed as typical “off” leakage is 100
microamperes with full primary voltage supplied from the battery. The VMODE pad is used to
switch between high and low power modes to reduce current consumption and gain in the
back – off conditions. VBA is used to further control the current consumption in the low
power mode.
This small package uses Skyworks’ low cost, multi - layer laminate substrate technology and
is approximately half the size of individually packaged component solutions. The SKY77455
front-end module can save handset and data card designers significant board space and
design-cycle time, and significantly simplify supply chain and sourcing of RF components.