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Technology has long provided an edge for most military forces, whether on land, at sea, or in the air. Advanced electronic technologies have often begun inside secure laboratories at facilities such as the Army Research Laboratory (ARL) or the Naval Research Laboratory (NRL), and much of the early work in high-frequency electronics can be traced back to vacuum tubes.

Anyone who has carried a chassis containing those large vacuum tubes and their even larger power supplies knows that technology often moves in the direction of smaller and lighter. Current advances in solid-state RF/microwave power—including discrete devices and amplifiers based on gallium nitride (GaN) semiconductors—have received a great deal of attention and funding from such defense-driven organizations such as the Defense Advanced Research Projects Agency (DARPA) and the US Department of Defense (DoD).

GaN certainly must be considered a “major” technology for future defense systems, since it can be used to boost signal strength from RF through millimeter-wave frequencies. Lasers and laser-based weapons are another area of interest, and what might be considered another major area.

The power densities of GaN devices are quite impressive, enabling high-power RF/microwave amplifiers to be constructed in a fraction of the size of those old vacuum-tube amplifiers. Of course, engineering of any kind involves tradeoffs, and achieving higher solid-state output power from smaller footprints requires dependable performance from what are often overlooked or “auxiliary” technologies, such as packaging and thermal-management materials.

Certainly, such materials and packaging are not considered auxiliary by the companies that develop and manufacture them. But they are essential to the success of truly high-power GaN amplifiers—not to mention, any possible semiconductor technologies that may follow GaN in the ongoing quest to replace tubes for generating high-power RF/microwave signal levels.

Such auxiliary technologies make it possible to pack many high-power GaN transistors into a single compact amplifier housing without causing overheating and meltdown. Unfortunately, any transistor wastes a great deal of supplied energy as heat, leaving suitable packaging and thermal management materials to conduct heat away from the source.

In military applications, they must do so continuously, and under a wide range of temperatures, humidity, and other environmental conditions around the world (and sometimes in outer space). For a high-power semiconductor technology such as GaN to deliver high performance under such rigorous conditions, it is the packaging and the thermal-management materials that help to protect the GaN devices and to contribute to a long operating lifetime.

Admittedly, GaN gets a great deal of attention for its high power densities in military and commercial applications. The semiconductor technology is widespread, found in everything from cell phones to automotive radar systems. But for it to endure for the long term in the harshest operating conditions, in aerospace and defense electronic systems, GaN must be protected by those “auxiliary” technologies, and such important components as packaging and thermal-management materials should not be overlooked.

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