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RF3404

RF3404 PCBA F

RF Micro Devices 

Preliminary

RF3404

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 +2.75VDC 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 880MHz. 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

Rev A1 010918

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 +8dBm. The PCS mixer

features 13dB 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-

caler for systems that have migrated to a single VCO

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

matched to 50Ω. The LO outputs can be tied together

externally to support single transmit LO applications

8

and each is matched to 50Ω.

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 1.0mm 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

8-41

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