M542 Datasheet, PDF (1/4 Pages) M/A-COM Technology Solutions, Inc. – Electrical Characterization of Packages for Use with GaAs MMIC Amplifiers

Application Note
M542
Electrical Characterization of Packages for Use with GaAs
MMIC Amplifiers
Rev. V4
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
Manufacturer
Kyocera
Kyocera
StratEdge
Kyocera
Kyocera
Mini-Systems
Mini-Systems
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.
Leadless, 8 port, ceramic
Oxley
Leadless, 10 port, ceramic
Alcoa
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
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