The semiconductor gallium nitride (GaN) is starting to replace gallium arsenide (GaAs) as the material of choice to build military electronics such as transmit/receive (T/R) modules found on new radar systems and jammers.

Industry watchers have long predicted the new semiconductor would supplant the older GaAs technology once the material became easier to produce and devices utilising the technology overcame reliability issues.

Two prominent US Navy programmes, the service's next-generation jammer (NGJ) pod and the Air and Missile Defense Radar (AMDR) are leading the charge to switch to the new technology. Both programmes, which will need to transmit radio signals at exceptionally high power levels, are relying on the new material to meet performance objectives.

GaN-based transistors can operate at much higher temperatures and work at much higher voltages than GaAs equivalents.

Raytheon, recently selected to develop the technology for the NGJ pod, says the new material is many times more efficient. "GaN RF [radio frequency] amplifiers can provide more than [five times] the power per element of GaAs in the same footprint," it says. "Fewer high-power GaN MMICs [monolithic microwave integrated circuits] could be used to replace many low-power GaAs MMICs or, alternatively, equal-power GaN chips can be made dramatically smaller."

Defeated rival BAE Systems is protesting to the US Government Accountability Office over Raytheon's NGJ technology development contract, but BAE also based its solution on GaN-based T/R modules. The same was true of Northrop Grumman/ITT's bid to develop the NGJ system.

Meanwhile, the US Navy's AMDR programme to replace the Lockheed Martin SPY-1 phased array radar on its Aegis-class warships will also rely on GaN technology. However, the two programmes are merely the tip of the iceberg. As the technology matures, it is likely to start replacing GaAs on many other applications.

Raytheon, for example, is working on growing sheets of artificial diamonds, which would be bonded with GaN-based semiconductors to further enhance cooling. If it works, the technology could become the core of future radar, communications and electronic warfare systems that would be smaller and more efficient than current systems.

Source: Flight International