Preliminary
8-41
RF3404
Rev A1 010918
8
Overview
Why Design with Receive Modules?
The RF3404 is a fully integrated dual-band, tri-mode
module contains an LNA, RF image-rejection SAW fil-
ter, mixer, mixer preamplifier, and local oscillator (LO)
buffer amplifiers as shown in the block diagram. The
module also contains all of the RF matching compo-
nents, bias-setting components, and decoupling com-
ponents required. The differential IF output matching is
external to the module in part due to the varying range
of IFs used by customers and the physical size of IF
SAW filters. The module, which measures only
8.0mmx8.0mm and takes up only 64mm2 of PCB
area, is less than half the size of available alternative
solutions, which typically occupy over 200mm2 of
board area. The RF3404 is control-compatible with
existing IF-to-baseband solutions.
Electrical Design Overview
The heart of the module is the RF2489 SiGe monolithic
microwave integrated circuit (MMIC) based on a high-
performance silicon germanium (SiGe) process. The
SiGe process is capable of fabricating transistors with
an Ft of 47GHz. The module achieves 30dB of gain
control in the 880MHz band. The gain-control range is
obtained with switches around the LNA and mixer
preamplifier. By itself, the cellular LNA features 15dB
small-signal gain and a typical noise figure of 1.1dB
when drawing 6mA current from a +2.75 VDC supply.
A CMOS-enabled control line makes it possible to
select an increased LNA input third-order intercept
point of +10dBm to meet the cross modulation require-
ments
of
the
IS-95B
CDMA
specification.
The
RF3404's LNA is followed by a miniature RF SAW filter.
It provides RF image rejection as well as transmit-band
rejection. All impedance matching to the RF SAW filter
is contained within the module. The module's RF2489
SiGe MMIC contains two high-frequency mixers that
handle downconversion of the CDMA and AMPS sig-
nals at 880 MHz. The module provides a common IF
port for the CDMA cellular and PCS band output signal
and a separate IF output port for the AMPS-band IF
signal. The mixers and their integrated preamplifiers
achieve a noise figure of 7dB, gain of 14dB, and input
third-order intercept point of +3dBm. A bypass switch
around the mixer preamplifier is integrated to support
those systems using a two-step gain approach for
meeting the three test conditions of IS-95B intermodu-
lation performance
The 1960MHz PCS CDMA signal path is similar to the
cellular path in many ways. The PCS LNA has a typical
gain of 16dB with a noise figure of 1.3dB. The LNA can
also be bypassed and also has a setting for high input
third-order intercept point of +8 dBm. The PCS mixer
features 13 dB gain, 7dB noise figure, and input third-
order intercept point of +3dBm. Again, all of the RF
impedance matching to the LNA and SAW filters is
included in the module.
The RF3404 module is flexible enough to accommo-
date either single or dual voltage-controlled-oscillator
(VCO) architectures. The cellular band has the select-
able option of running the LO directly to the cellular
mixers or routed through a divide-by-2 frequency pres-
calerfor systemsthat havemigratedtoasingleVCO
architecture. A buffered transmit LO output with
-12dBm output power is also supplied for both the PCS
and cellular bands. The RF3404 requires an input LO
power range of -10dBm to -4dBm. The LO input port is
matchedto50
Ω. The LO outputs can be tied together
externally to support single transmit LO applications
and each is matched to 50
Ω.
Mechanical Layout Overview
The RF3404 is built around a laminate module technol-
ogy geared to high-volume manufacturing and the low
cost structure mandated by the wireless industry. RF
Micro Devices has already built millions of power
amplifier (PA) modules using the same materials sets,
supply chain, and manufacturing rules used for the
RF3404.
The module is overmolded with a compound that has a
finished overall thickness of 1.6mm. The backside pat-
tern of the 8.0mm x8.0mm module is a 48-pin land grid
array (LGA) with a double row of input/output (I/O) con-
nections to ease trace routing as shown in the interface
outline drawing. A total of 21 of these I/O pads are
actual signal interconnections, with the remainder
being ground connections.
The I/O pads are a generous 0.5mmx0.6mm in size
on a 1.0 mm pitch. The outer ring of I/O pads contains
all of the RF connections along with the voltage supply
and some control lines. The inner ring of I/Os contains
only DC control signal lines and VCC connections. A
1.5mm square ground pad in the center of the module
backplane supplies additional RF grounding and also
assures a very robust mechanical attachment to the
cellular/PCS telephone PCB. The dual row I/Os aid in
the telephone PCB layout by reducing the number of
Chinese ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
