Ultralow Loss GSM Quad-Band Antenna Switch Module
CXG1180EQ/1186EQ
Multiband support to allow the use of the multiple frequencies that are
used in different countries is now standard in GSM terminals, which
are now the most widely used terminal worldwide. Thus there are es-
pecially strong desires for miniature, low-cost, low-loss devices that
can switch between multiple circuits with differing frequencies. The
newly-developed CXG1180EQ and CXG1186EQ are high-performance
lead frame modules that achieve those requirements in a balanced
manner.
The GSM/UMTS dual mode CXG1190EQ/AEQ products introduced in
CX-News Volume 38 are also high-performance lead frame modules.
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Ultralow insertion loss: 0.70 dB in the
GSM 850/900 Tx path and 0.85 dB in
the DCS/PCS Tx path
Dual low-pass filters:
Attenuation 30 dB typical
(GSM Tx 2fo, DCS/PCS Tx 2fo)
Lead frame module that adopts a mold
array package
Miniature low-height package:
LQFN-28P-01
(4.5 mm
×
3.2 mm
×
1.3 mm max.)
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Switching Structure that
Achieves Low Insertion Loss
Insertion loss is an important index for
switch performance. This parameter
contributes significantly to both current
consumption during transmission and
reception sensitivity in portable terminals.
Switch modules using the conventional
LTCC* substrate adopted a structure in
which the frequency band was divided into
a low band (900 MHz band) and a high
band (1800/1900 MHz band) using a
diplexer, and after that, the path switches
were connected. (See figure 1.) In these
products, Sony adopted the SP6T switch
structure to achieve low loss. These
devices also provide a low-pass filter in
the GSM Tx path. (See figure 2.) In the
conventional LTCC module structure, the
insertion loss for all the paths becomes the
sum of the losses for the diplexer and the
path switching switch. As a result, the
overall loss was quite large.
In contrast, in the SP6T structure, only the
switch insertion loss occurs in the paths
other than the GSM Tx path, thus achiev-
ing low loss. Low loss can be achieved
for the GSM Tx path as well, since the
LPF can be implemented with a lower in-
sertion loss than the diplexer. Further-
more, these devices achieve ultralow loss
and low distortion by using GaAs switches
implemented using Sony's unique
JPHEMT process as the switching de-
vices.
*:
LTCC: Low temperature co-fired ceramic
achieves both high performance and high
integration densities and high integration
density filters using LTCC technology. By
using existing package technology based
on lead frames, it was possible to use
current manufacturing and assembly
equipment and processes, and thus Sony
is able to supply quality products at low
cost. Furthermore, since these products
consist of two simple components, a GaAs
switching IC and a low-pass filter, they
have the advantage that the development
TAT can be reduced.
Lead Frame Module
In conventional antenna switch modules
used in GSM terminals and other prod-
ucts, the switches are implemented by
combining, on an LTCC, FR-4, or similar
substrate, PIN diodes and other semicon-
ductor switching elements and multiple
passive devices inserted on the substrate.
However, considering the demands for
multimode and multiband operation, min-
iature low-height form factors, and lower
costs in recent cellular phone products, it
can easily be seen that it will be difficult
to achieve these using these conventional
structures. Sony's response to these issues
was to use the mold array package, which
uses lead frames and is an existing pack-
age technology. These new products are
implemented by mounting, on the lead
frame, both GaAs switches fabricated us-
ing Sony's unique JPHEMT process that
Miniature Low-Height Form
Factor
The mounting area was reduced by inte-
grating the two low-pass filters for the Tx
paths (two circuits) into one component
using LTCC technology. Also, etching
technology can be used to perform com-
plicated machining on the lead frame,
which plays the role of interface between
the switch and low-pass filter components
mounted on the lead frame.
Furthermore, Sony optimized the contact
area between the internal low-pass filter
lands and the lead frame and also opti-
mized the mold sealing thickness above
the low-pass filters, thus achieving a min-
iature low-height form factor.
V
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I
C
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The CXG1180EQ and CXG1186EQ
are antenna switches that feature
low loss. While the function they
provide is simple, this component
has a large influence on the per-
formance of radio transceivers.
While this could be said to be ex-
cessive concern for such a small
point, I hope this will contribute to
our customers’ creation of superb
radio products.
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