Application Note
M542
Electrical Characterization of Packages for Use with GaAs
MMIC Amplifiers
Abstract
A test methodology will be presented which combines
the advantage of on-wafer RF probing with a TRL
calibration to create a completely de-embeddable,
novel “test fixture” capable of electrically characteriz-
ing most any style package or device. This scheme
has been used to characterize many of the currently
available microwave packages in order to identify ap-
propriate packages for our MMIC amplifier products
which cover frequencies up to 12 GHz. In addition,
the technique has been employed to characterize in-
jection-molded plastic packages and to evaluate non-
probeable MMIC's.
Package Description
5 lead, ceramic
6 lead, ceramic
Leadless, 6 port, ceramic
7 lead, ceramic
8 lead, ceramic
8 lead, glass
8 lead, glass, ground straps
Leadless, 8 port, ceramic
Leadless, 10 port, ceramic
Kyocera
Kyocera
StratEdge
Kyocera
Kyocera
Rev. V4
Manufacturer
Mini-Systems
Mini-Systems
Oxley
Alcoa
Introduction
Most package vendors have very little microwave
design and characterization capability. Their lim-
ited characterization efforts typically involve the use
of poor fixturing, which obscures the true frequency
response of the package. Companies specializing
in fixturing, while investing considerable mechani-
cal engineering effort, expend far less on electrical
considerations, often producing fixtures inadequate
for use at microwave frequencies. Consequently,
there is very little microwave performance data
available from package vendors.
Therefore, to evaluate and identify candidate pack-
ages for each of the amplifiers in our MMIC ampli-
fier product line, specific fixturing had to be devel-
oped for each package style considered. A novel
fixturing approach was designed and implemented,
which not only eliminates the need for expensive,
package specific fixtures, but also overcomes the
frequency limitations of traditional connectorized,
plunger-style fixtures. Additionally, a rigorous cali-
bration method was developed which allows com-
plete fixture de-embedding.
This test methodology is applicable to practically
any style device. Table 1 lists the package styles
investigated. Through this work, proper electrical
characterization of commonly used packages has
indicated useful frequency ranges broader than
expected by even the package manufacturers.
This finding has allowed us to use low-cost pack-
ages for frequency applications where our competi-
tors typically resort to high-priced custom pack-
ages.
Table 1. Summary of Packages
Design Approach
To eliminate the need for expensive, device spe-
cific, traditional fixtures and overcome their fre-
quency limitations, an RF probeable ceramic sub-
strate was designed as the interface to the device-
under-test (DUT). Figure 1 illustrates this coplanar
probe to microstrip transition. It is a 50 ohm line
fabricated on 10-mil thick alumina, with an 8-mil
pitch, ground-signal-ground (G-S-G) probe pattern
at one end. The two ground pads are connected to
the substrate backside with 8-mil diameter plated
vias. The G-S-G pattern can be probed using com-
mercially available microwave probes on a stan-
dard microwave probe station. The opposite end of
the substrate can be bonded to a test port of the
DUT.
To complete the “test fixture,” only a thin brass
block is required to serve as the mounting surface
for the ceramic substrates and the DUT. If neces-
sary, the brass block could be machined to com-
pensate for any difference in height between the
substrate and DUT test port. To fixture practically
any DUT, all that is needed is a brass plate and the
probeable ceramic substrates. Figure 2 shows the
configuration used for characterizing our
MAAM71200-H1, a packaged 7-12 GHz GaAs
MMIC low noise amplifier.
1
Visit www.macomtech.com for additional data sheets and product information.
•
North America
Tel: 800.366.2266 •
Europe
Tel: +353.21.244.6400
•
India
Tel: +91.80.4155721
•
China
Tel: +86.21.2407.1588
M/A-COM Technology Solutions Inc. and its affiliates reserve the right to make
changes to the product(s) or information contained herein without notice.
Application Note
M542
Electrical Characterization of Packages for Use with GaAs
MMIC Amplifiers
Rev. V4
To demonstrate the package characterization
method, the evaluation of a standard Kyocera 8-
lead ceramic flat pack will be examined. Figure 4
shows how one feedthrough structure in the wall of
this package was tested. Package leads were cut
close to the package body, and the ceramic sub-
strates were mounted flush to the package ports.
Two short 3-mil wide gold ribbons bond the sub-
strates to the package.
Figure 1. Probeable Ceramic Substrate
Similarly, sealed packages with leads internally
terminated with 50 ohm chip resistors were tested
to determine the cross-coupling between opposite
and adjacent leads. Through-lines within sealed
packages were also measured. With this data, the
true electrical performance of the package was de-
termined and models for the feedtrhough and cou-
pling were developed.
Figure 2. Fixtured MAAM71200-H1
To de-embed this “test fixture,” a set of through-
reflect-line (TRL) standards was employed. A
“zero-length” through, a short, and two delay lines
were fabricated. These standards, shown in Figure
3, are used with the common TRL de-embedding
algorithm. This allows any measurement made
with the probeable ceramic substrates to be de-
embedded to yield data for only the DUT with con-
necting bonds. Bond wires can also be de-
embedded by first characterizing and modeling
them using this same “probeable ceramic” tech-
nique. For this work, multiple bond wire and ribbon
lengths were characterized to generate fully scal-
able bond models.
Figure 4. Fixtured Feedthrough
This information allows the identification of an ap-
propriate package for existing MMIC products and
provides an accurate model for incorporating pack-
age effects into future design work.
Figure 3. TRL Calibration Standards
2
Visit www.macomtech.com for additional data sheets and product information.
•
North America
Tel: 800.366.2266 •
Europe
Tel: +353.21.244.6400
•
India
Tel: +91.80.4155721
•
China
Tel: +86.21.2407.1588
M/A-COM Technology Solutions Inc. and its affiliates reserve the right to make
changes to the product(s) or information contained herein without notice.
Application Note
M542
Electrical Characterization of Packages for Use with GaAs
MMIC Amplifiers
Experimental Results
The feedthrough walls of each package listed in
Table 1 have been tested and modeled. This
feedthrough data alone largely indicates the useful
frequency range of each package. Figure 5 shows
the frequency response for the feedthrough of the
8-lead ceramic flatpack. This package, previously
thought to be useful only at lower frequencies,
demonstrates excellent performance well into X-
band before resonating. Based on this result, we
assembled our 2-8 GHz GaAs MMIC amplifier into
this package. The performance of this packaged
amplifier, part number MAAM28000-A1, is shown
in Figure 6.
Rev. V4
Figure 8 shows the measured versus modeled in-
sertion loss and input return loss for this package
feedthrough. The model simulates the feedthrough
performance closely over the useful frequency
range of the package.
Figure 7. Feedthrough Model
Figure 5. Feedthrough Frequency
Response
20
15
10
5
0
-5
-10
-15
-20
0
2
4
6
8
10
Gain
S11
S22
Figure 8. Measured vs. Modeled
Performance
Coupling effects between package ports were also
measured and modeled. A Y-parameter extraction
showed that the coupling could be attributed to
equivalent capacitance values. In the case of the
8-lead ceramic flatpack, coupling between adjacent
ports along one side of the flatpack can be repre-
sented by a 0.03 pF capacitance. Between alter-
nate ports along the same side, the coupling ca-
pacitance is nominally 0.003 pF. Coupling be-
tween internally terminated ports on opposite sides
of the flatpack was modeled with a 0.0007 pF ca-
pacitor. This coupling model accurately predicts
the measured input to output isolation, as illus-
trated in Figure 9, over the package’s useful fre-
quency range.
Frequency (GHz)
Figure 6. MAAM28000-A1 Performance
Using the de-embedded feedthrough data, Y-
parameter extraction followed by a constrained op-
timization was performed to derive the feedthrough
model shown in Figure 7.
3
Visit www.macomtech.com for additional data sheets and product information.
•
North America
Tel: 800.366.2266 •
Europe
Tel: +353.21.244.6400
•
India
Tel: +91.80.4155721
•
China
Tel: +86.21.2407.1588
M/A-COM Technology Solutions Inc. and its affiliates reserve the right to make
changes to the product(s) or information contained herein without notice.
Application Note
M542
Electrical Characterization of Packages for Use with GaAs
MMIC Amplifiers
-20
-30
DB (S21) COUPMOD
DB (S21) R317COUP
Rev. V4
-40
Bond wires, bond wire pairs and ribbons have also
been characterized with this test method, resulting
in scalable, empirically-derived models. In addi-
tion, this test methodology is widely employed in
our engineering test lab to RF probe MMICs which
are otherwise not RF probeable.
P/N (MAAM-)
Function
0.2-3.5 GHz
1-2 GHz
2-3 GHz
3-7 GHz
7-12 GHz
2-8 GHz
2-6 GHz
IFA
LNA
LNA
LNA
LNA
WBA
PA
Package Style
8 lead, ceramic
8 lead, ceramic
8 lead, ceramic
8 lead, ceramic
Leadless, 6 port
ceramic
8 lead, ceramic
7 lead, ceramic
-50
-60
02350-A2
-70
0
2
4
6
8
10
12
12000-A1
23000-A1
37000-A1
71200-H1
28000-A1
26100-B1
Frequency (GHz)
Figure 9. Package Isolation
Characterizing the packages in Table 1 produced
interesting results. The five relatively inexpensive
packages (the 5-, 7-, and 8-lead flatpacks) are
commonly used for fairly low frequency applica-
tions. However, as detailed above, the 8-lead ce-
ramic flatpack, supplied by Kyocera, exhibits excel-
lent performance into X-band. Mini-Systems’ 8-
lead glass flatpack also exhibits excellent perform-
ance into X-band, and their version with ground
straps has similar performance through C-band.
The Kyocera 5- and 7-lead ceramic flatpacks, often
used in switching applications, have higher inser-
tion loss and lower return loss, but demonstrate
reasonably good performance into X-band and C-
band, respectively. The Oxley manufactured lead-
less 8-port ceramic package has excellent perform-
ance through C-band.
The remaining three packages shown in Table 1
are all advertised for high frequency applications.
Of these, StratEdge’s leadless 6-port ceramic flat-
pack exhibits the best performance through 20
GHz. The Alcoa 10-port ceramic package also
works reasonably well up to 20 GHZ. Kyocera’s
leaded version of the 6-port ceramic package dem-
onstrates reasonably good performance to 16 GHz.
At least one suitable package was chosen for each
of the small signal amplifiers, and one of the power
amplifiers, in our GaAs MMIC amplifier product
line. Table 2 lists all the packaged amplifiers now
offered as standard products. This test method
was also used to characterize the lead parasitics of
the SOP and SSOP plastic packages. That data
has been incorporated into the design of several
new products specifically targeted for high-volume,
low-cost, commercial applications.
4
Visit www.macomtech.com for additional data sheets and product information.
Table 2. Packaged Amplifier Products
A novel fixturing and test methodology has been
designed and implemented which allows accurate
microwave frequency characterization of virtually
any device. This approach has been used to
evaluate many of the currently available microwave
packages. Appropriate packages have been identi-
fied for our GaAs MMIC amplifiers, resulting in
many new standard products. Models for package
feedthrough structures, plastic packages, and bond
wires and ribbons have all been developed using
this method.
Acknowledgements
Written by Stephen R. Smith and Michael T. Mur-
phy. The authors thank Scott Mitchell and Ted
Begnoche for testing these devices, Brenda Mil-
inazzo for assembling them and Bill Fahey for help-
ing to prepare this paper.
©
1993 IEEE.
This paper first appeared in the IEEE
1993 MTT-S International Microwave Symposium Digest and is
reprinted here with the permission of IEEE
.
•
North America
Tel: 800.366.2266 •
Europe
Tel: +353.21.244.6400
•
India
Tel: +91.80.4155721
•
China
Tel: +86.21.2407.1588
M/A-COM Technology Solutions Inc. and its affiliates reserve the right to make
changes to the product(s) or information contained herein without notice.
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