Application Note
M540
GaAs MMIC Low Noise Amplifier SOIC-8 Platform
Rev. V3
The AM50-0002 employs a combination of the LG and
HG designs to create a three stage, higher gain, LNA.
The AM50-0002, however, uses a simple external input
matching network to obtain minimum noise figure. A
detailed discussion of this external matching network is
contained in the section on customer use considerations.
In this product platform there are essentially two circuit
design types, a low gain (LG) and a high gain (HG). The
LG design (MAAM12022, MAAM12032, MAAM22010,
and AM50-0001), shown in Figure 3, employs a single
stage cascade configuration with series feedback to si-
multaneously achieve impedance match and minimum
noise figure.
The HG design (MAAM12021 and
MAAM12031), shown in Figure 4, uses two cascaded
common source stages biased in series to achieve the
high gain at low current consumption, and also employs
series feedback to simultaneously achieve impedance
match and minimum noise figure. The AM50-0002 em-
ploys a combination of the LG and HG designs to create
a three stage, higher gain, LNA. The AM50-0002, how-
ever, uses a simple external input matching network to
obtain minimum noise figure. A detailed discussion of
this external matching network is contained in the section
on customer use considerations.
The MMIC layout of Figure 5 is the MAAM12021, the
largest chip of the family; it measures 1 mm on a side.
Figure 6 illustrates the assembly of this MMIC into the
SOIC-8 package. Immediately one notices that the lead
frame is split and there is more than one chip in the plas-
tic package. The amplifier employs a custom fused split
paddle lead frame to ensure unconditional stability when
used on a typical FR4 board application. The other chip
in the package is a metal-nitride-silicon (MNS) single-
layer capacitor used for internal RF by-passing to allow
biasing from a single positive 3-5 V supply. These MNS
capacitors, supplied by M/A-COM’s Semiconductor Busi-
ness Unit, have almost ideal performance for very little
cost. After assembly, the MAAM12021 has the func-
tional diagram as shown in Figure 7. Six of the seven
LNAs in this product platform share these assembly and
functional diagrams. The AM50-0002 utilizes a slightly
different lead frame and pin assignment to accommodate
the special requirements of its three stage, high gain
design.
MMIC Manufacturing Considerations
The MMIC LNAs are automatically assembled onto cus-
tom designed, fused, split paddle lead frames as shown
previously in Figure 6. Careful consideration is given to
die placement, both for the GaAs MMIC LNA and the
MNS capacitor, to ensure repeatable bond wire induc-
tance and good mechanical strength for reliability. The
ground leads are fused to ensure low inductance
grounds as well as low thermal impedance. These fused
ground leads also lower cost in volume production by
eliminating eight ground bonds (2 per lead). Once as-
sembled onto the lead frames, the assembly is transfer
molded with a plastic which has both good moisture re-
sistance properties for reliability and well controlled di-
electric constant for repeatable RF performance. Fully
assembled MMIC LNAs are stored in antistatic tubes,
ready for automatic test.
Fully assembled MMIC LNAs are 100% RF tested for
compliance against the guaranteed data sheet perform-
ance of gain, nose figure, and DC current. Standard
automatic digital IC testers have been modified to make
rapid RF measurements. Accuracy is maintained by
establishing correlation coefficients between the high
speed automated production testers and the highly accu-
rate engineering measurement system.
Quality and Reliability
The MMIC LNA products are subjected to a one-time
product qualification, either before product releases or
when there is a major process change. In the case of
the MMIC LNAs, the one-time qualification, according to
Table 1, has established the MMIC LNA product family to
be capable of serving the high volume global commercial
electronics market with a 400-FIT reliability rate (300
devices at an activation energy of 0.7 eV, normal operat-
ing temperature of 85˚C, and 90% confidence level).
The MMIC LNAs are also ESD classified as low level
class 1—as low as 350 volts can induce damage. Table
2 shows the on-going quality monitoring of plastic pack-
aged devices in production to maintain the established
level of product quality.
This 400-FIT reliability level is established at a junction
temperature of 150˚C or less. This is the reason for the
maximum rating on the data sheet of 150˚C or less. The
junction temperature can be calculated from the product
of the thermal resistance and power dissipated. The
thermal resistance for the MMIC LNAs is 165˚C/W on all
LNA’s, except for the AM50-0001 where it is 125˚C/W.
3
Visit www.macomtech.com for additional data sheets and product information.
•
North America
Tel: 800.366.2266 •
Europe
Tel: +353.21.244.6400
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India
Tel: +91.80.4155721
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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.
MA-COM [ M/A-COM TECHNOLOGY SOLUTIONS, INC. ]
