Size, Weight and Power Constraints

Two teams of DARPA performers have achieved world record power output levels using silicon-based technologies for millimeter-wave power amplifiers. RF power amplifiers are used in communications and sensor systems to boost power levels for reliable transmission of signals over the distance required by the given application. These breakthroughs were achieved under the Efficient Linearized All-Silicon Transmitter ICs (ELASTx) program. Further integration efforts may unlock applications in low-cost satellite communications and millimeter-wave sensing.

The submillimeter wave, or terahertz, part of the electromagnetic spectrum falls between the frequencies of 0.3 and 3 terahertz, between microwaves and infrared light. Historically, device physics has prevented traditional solid state electronics (microchips) from operating at the terahertz scale. Unlocking this band’s potential may benefit military applications such as high data rate communications, improved radar and unique methods of spectroscopy—imaging techniques that provide better tools for scientific research. However, access to these applications is limited due to physics.

Many existing compact, high-data-rate millimeter-wave wireless communications systems use integrated circuits (ICs) made with gallium arsenide (GaAs) or gallium nitride (GaN). These circuits provide high power and efficiency in small packages but are costly to produce and difficult to integrate with silicon electronics that provide most other radio functions. Silicon ICs are less expensive to manufacture in volume than those with gallium compounds but until now have not demonstrated sufficient power output and efficiency at millimeter-wave frequencies used for communications and many other military applications, such as radar and guidance systems.

Officials from Guinness World Records today recognized DARPA’s Terahertz Electronics program for creating the fastest solid-state amplifier integrated circuit ever measured. The ten-stage common-source amplifier operates at a speed of one terahertz (1012 Hz), or one trillion cycles per second—150 billion cycles faster than the existing world record of 850 gigahertz set in 2012.

Many essential military capabilities—including autonomous navigation, chemical-biological sensing, precision targeting and communications—increasingly rely upon laser-scanning technologies such as LIDAR (think radar that uses light instead of radio waves). These technologies provide amazing high-resolution information at long ranges but have a common Achilles heel: They require mechanical assemblies to sweep the laser back and forth. These large, slow opto-mechanical systems are both temperature- and impact-sensitive and often cost tens of thousands of dollars each—all factors that limit widespread adoption of current technologies for military and commercial use.