1. The Solid State Power Amplifier (SSPA), which in 2014 was certified by Guinness World Records as the world’s fastest solid state chip, able to operate at THz speeds. This device, made of the semiconductor indium phosphide (InP), also can boost the power of a wide swath of incoming signals some thirtyfold (that’s what the “15 dB GAIN” spec in the poster indicates).
The papers that are online appear to be early work by Grumman.
Solid-State Amplifiers for Terahertz Electronics by Northrop Grumman
With the fMAX of current generation InP transistors pushing above 1-THz and new transistor scaling in progress, the operational frequency of solid-state amplifiers is being pushed towards THz frequencies. In this paper we present out latest work towards demonstrating THz frequency amplifiers, including measured gain and noise performance of a 0.48 THz low noise amplifier using scaled InP transistors. Initial performance of next generation transistors is also presented, along with infrastructure necessary to package and operate solidstate amplifiers at THz frequencies.
2. Micromachined Traveling Wave Tube Amplifier (TWTA), a miniaturized device that relies on a tiny vacuum chamber in which electrons and radio signals interact. This device can boost the power of a narrower range of THz frequencies by a factor of about 200 and was a celebrated darling of the 2016 IEEE International Vacuum Electronics Conference.
Both of them made by Northrop Grumman and are breaking down the technical barriers to make THz applications possible. “Together, the world-record SSPA and highly-acclaimed TWTA open the way to a THz future featuring devices that can generate, detect, process, and radiate extremely high-frequency signals, and push what is possible in areas ranging from high-resolution security imaging, collision-avoidance radar, high data rate communications, and remote detection systems for dangerous chemicals and explosives.”
Here is a 2010 paper on Traveling Wave Tube Amplifiers
SOURCES - DARPA