Agencies such as the Department of Homeland Security (DHS), the Department of Commerce (DoC), the National Oceanic and Atmospheric Administration (NOAA), the National Weather Service (NWS), the Department of Transportation (DoT) and the Federal Aviation Administration (FAA) as well as the commercial wireless industry now also recognize the utility and cost-effectiveness of AESA-based sensor and communication systems. In addition, multifunction AESA-based systems are becoming more capable with dynamic transmit and receive functionalities that enable the same system to perform multiple missions. Looking at the evolution of AESAs from the early 1970s to today, we see a dramatic increase in capability enabled by key technology developments in MMICs, radiating elements, receiver/exciters, beamforming and signal/data processing and packaging (Figure 1).

The early focus was at the high frequency (HF) to ultra-HF (UHF) bands, but today, AESAs operate from L-band through Ku-band and continue to extend into the millimeter-wave band, enabled by advances in gallium arsenide (GaAs), silicon (Si) and mixed signal devices. Gallium nitride (GaN), now in production at Raytheon, has enabled the next generation of higher power, more efficient AESA-based products. These technology developments enable architectures that provide cost and performance trades with scalability and modularity that are now more easily integrated into a wider variety of platforms and applications. - See more at: http://www.raytheon.com/news/technology_today/2014_i1/aesa.html#sthash.0sDjnyBB.dpuf

Industry attention and movement from hybrid microwave integrated circuits to monolithicbased approaches began due to the requirements for low cost, mass production compatible circuits providing increased integration, reliability and multi-octave performance. Development of MMIC devices began in the early 1980s when gallium arsenide (GaAs) was emerging as the semiconductor of choice for efficiently amplifying and phase shifting RF signals. Efforts ramped up in the 1990s, as GaAs-based MMICs were introduced into large production programs for a new generation of phased array radars. Over time, the performance requirements of military systems became more challenging thus requiring further improvements to MMIC power, efficiency and low noise performance. GaN MMIC technology was pursued to help meet these new higher performance military system requirements. Raytheon’s long-term commitment to the development of GaN technology began nearly 15 years ago, and has leveraged its long history of GaAs semiconductor work, as well as partnerships with industry, academia and government. Raytheon’s development history with GaAs provided the needed infrastructure and lessons-learned experience to accelerate GaN’s development. This included the growth of starting material, the modeling of a GaN transistor’s RF performance, the semiconductor fabrication facility, the microwave and module design and the testing capabilities. Through early strategic partnering with Cree, the University of California Santa Barbara and U.S. government labs during the Defense Advanced Research Projects Agency (DARPA) Wide BandGap Semiconductors (WBGS) Phase II program, the team was able to shorten the cycles of learning and leverage each other’s findings to more quickly advance the state of GaN transistors (Figure 3).

Raytheon’s focus on early reliability demonstrations and transition to 4-inch wafers, to leverage the existing GaAs manufacturing facility, resulted in an industry leading manufacturing readiness level (MRL) of 8 accomplished under Raytheon’s Office of Secretary of Defense Title III program. In addition to GaAs and GaN MMIC development, our research and investments extend to customizing the many unique and prolific MMIC functions that make up our modules.

Our GaAs pseudomorphic high electron mobility transistor (pHEMT) technology development focused on the MMICs which provide the amplitude and phase control and enabled an efficient digital interface. The pHEMT process mixes RF and logic functions on the same GaAs MMIC. This optimizes efficient serial or parallel logic interfaces to a silicon (Si) controller chip which extends to the beam steering electronics. This unique capability in a GaAs MMIC enables logic functions locally and minimizes the number of off-chip components and interfaces, improving reliability, producibility and reducing the AESA’s size and cost. - See more at: http://www.raytheon.com/news/technology_today/2014_i1/aesa.html#sthash.0sDjnyBB.dpuf