Future
Trends for Compound Semiconductors in Military Systems
John
Zingaro
Northrop
Grumman Systems Corporation, MS 1105,
john.zingaro@ngc.com;
Improvements
in compound semiconductor technologies have formed the basis for rapid advances
in r.f. electronics. Requirements for
the military tend to differ from commercial applications. For example being out of range on your cell
phone is an inconvenience, but can have dire consequences for the
military. Thus the military will pay a
premium for the right performance. As a result military components tend to have
characteristics that may push beyond standard commercial MMICs. Many military devices are semi-custom
designs; most standard commercially available components are in the wrong bands
or give up too much performance for typical military applications. Quantities
can be small from 10’s to 10’s of thousands of components per year. Rarely does a need reach a commercial
threshold of a million parts per year.
Foundry runs are common for many military applications. Packaging costs tend to be significant, thus
highly integrated MMICs are desirable minimizing critical interfaces and the
number of components to be assembled.
Advanced systems use a wide range of compound semiconductor technologies
such as GaAs PHEMT, HBTs, InP, SiGe, MHEMT with SiC just becoming available and
GaN and the antimonides becoming available within the next few years. Demand for each technology is based upon two
factors. Each technology provides a
significant performance advantage and fabrication of multiple technologies can
be shared relatively efficiently on a single foundry line to provide sufficient
throughput to maintain process yields and cover the cost of capital. Some foundries are currently running GaAs
PHEMT, HBT, MHEMT and are gearing up for GaN. A final factor is the tie between
devices and packaging technologies.
Typical RF front ends include devices from several technologies,
i.e. GaAs, Silicon, SiGe integrated into
a single package. The marriage between
device and package must address issues such as DC/RF interfaces and interconnections,
thermal design, environmental factors applied to ever smaller form
factors. Trends in packaging will place
new requirements and constraints on compound semiconductors and how they are
used in future military systems.