SLX-2143 Datasheet, PDF (6/7 Pages) List of Unclassifed Manufacturers – 1700-2200 MHz High Linearity Low Noise Amplifier Module

Preliminary
SLX-2143 1700-2200 MHz LNA Module
Abstract
This application note describes the components and
materials that make up the SLX-2143 low noise amplifier
module. It also describes the circuit board layout required
for optimum performance, and procedures for reliable sol-
der attachment.
Introduction
The SLX-2143 is a thick film hybrid low noise amplifier
designed for 1.7 - 2.2GHz applications that require both low
noise figure and good linearity. This module is based on
conventional thick film circuit fabrication methods, and can
be surface mounted onto circuit boards using industry stan-
dard solder reflow techniques. In order to extract peak per-
formance from this amplifier, it is important to use an
appropriate circuit board layout, and to ensure that the part
is soldered down correctly. Please contact
[e-mail] if your application is between 2.2 - 2.5
GHz.
Materials
The base of the SLX-2143 is an alumina (ceramic)
“thick film” substrate, 0.015” (.38mm) thick. The back of this
substrate is metallized with plated copper (on a base layer
of fired silver) that has been protected with a thin flash of
nickel and gold to guarantee solderability, even after
extended storage time. The ceramic substrate has via holes
that are filled with a fired silver compound. On the compo-
nent side of the substrate (the side that is covered with the
lid) there are conductors based on plated copper (that are
protected with a flash of nickel-gold), and pure gold conduc-
tors. The copper conductors are formed by plating copper
onto a silver conductor that has been fired into the sub-
strate. The fired silver base ensures excellent adhesion to
the substrate, and the plated copper ensures that the silver
is completely protected. The gold conductors are fired into
the substrate and are used wherever wire bonds are
required. Thick film resistors are also integrated onto this
substrate. A glass passivation layer is used for additional
protection, and to act as a solder dam.
Inside the module there are several different types of
components in use. Solder terminated capacitors and
inductors are attached with high temperature lead free
(96.5% Sn 3.5% Ag) solder. Chip components are attached
with conductive silver epoxy and are connected to the rest
of the circuit with gold wire-bonds. The module is sealed
with a ceramic lid that is held down with a B-stage epoxy
seal ring. The overall module is non-hermetic, but it will
pass a standard “bubble” leak test.
The module is designed to be reflowed onto a laminate
based circuit board such as FR4. Input and output connec-
tions to the module are made with “castellations” on either
end of the module. Castellations are rounded metallized
notches (metallized with silver, copper, nickel, gold, as in
other parts of the module) in the edge of the ceramic sub-
strate. When these are put through a solder reflow process,
the solder tends to wick up into the notches, creating a
robust solder fillet that can be easily inspected. The third
connection, ground, is formed by the rest of the metal on
the back of the module.
Board Design
As the module has the input, output, and ground con-
nections on the same plane, in principal coplanar
waveguide should be used to feed the module. In practice,
microstrip can also be used as ground vias under the mod-
ule connect the “top” ground to a microstrip ground plane.
Care still needs to be taken to ensure a graceful transition
from microstrip to coplanar waveguide. Care also needs to
be taken to ensure that the medium leading up to the mod-
ule (be it microstrip, coplanar waveguide, or grounded
coplanar waveguide) is 50 ohms, with minimal loss. The
dimensions used in the evaluation board are recommended
(they yield a return loss of 27dB at 2 GHz) if that material
structure can be adapted.
The evaluation board layout is shown in Figure 1. The
DC blocks, bias inductor, and decoupling capacitors are
also shown on the board. The coplanar line leading up to
the module has a width of 0.04” (1.0mm) with a spacing of
0.02” (0.5mm) to the coplanar ground. The thickness of the
board dielectric, FR4, is 0.032” (0.81mm), although typically
the overall board thickness is increased with additional lay-
ers. One ounce copper is used on both sides. At 2.5GHz,
the performance of the FR-4 board material is becoming
marginal, so users may find it necessary to adjust the tuning
of the part with external turning elements if operating at this
frequency.
Sirenza Microdevices will provide the detailed layout (in
AutoCAD format) to users wishing to use the same layout
and materials.
522 Almanor Ave., Sunnyvale, CA 94085
Phone: (800) SMI-MMIC
6
http://www.sirenza.com
EDS-102501 Rev B