DARPA creates solid state receiver that operates at 0.85 terahertz

ARLINGTON, Va., 4 Aug 2012. In an effort to create advanced communication and sensor systems, DARPA has designed a solid state receiver that demonstrates gain at 0.85 terahertz (THz). This was created as part of DARPA's THz electronics program, the goal of which is to enable transistor-based electronics that will operate at THz frequencies. Imaging, radar, spectroscopy, and communications systems operating in the millimeter wave sub-MMW frequency bands have been difficult to create due to a lack of effective means to generate, detect, process, and radiate the necessary high frequency signals. In order to control and manipulate radiation in this portion of the RF spectrum, electronics need to be developed that can operated at frequencies past 1 THz.

The sub millimeter wave (sub-MMW) frequency band begins at frequencies above 300 gigahertz (GHz) where the wavelengths become less than 1 mm. Until recently, active electronics using solid-state technologies were unable to access sub-MMW frequencies directly due to poor transistor performance. The compromise for electronic options was to use frequency conversion to multiply circuit operating frequencies up from millimeter wave frequencies. This approach limited the output power level of the devices and the achievable signal-to-noise ratio while also restricting the devices to larger sizes in terms of footprint and weight. These restrictions prevented widespread implementation and the subsequent exploitation of the sub-MMW frequency band. The enabling technology necessary to exploit the sub-MMW band is monolithic microwave integrated circuits (MMICs) that will operate up to THz frequencies. These THz MMICs, or TMICs, require THz transistors with maximum oscillation frequencies (fmax) above 1 THz.

The objective of DARPA's terahertz (THz) electronics program is to develop the critical device and integration technologies necessary to realize compact, high-performance electronic circuits that operate at center frequencies exceeding 1.0 THz.