Wednesday, October 24, 2012

Darpa closing in on solid state receivers which operate at 1 THz




Imaging, radar, spectroscopy, and communications systems operating in the millimeter wave sub-MMW frequency bands have been elusive 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 especially challenging portion of the RF spectrum, electronics must be developed that can operated at frequencies past 1 THz.
The sub millimeter wave (sub-MMW) frequency band begins at frequencies above 300 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 insufficient transistor performance. The compromise electronic option was to use frequency conversion to multiply circuit operating frequencies up from millimeter wave frequencies. Such an approach limited the output power level of the devices and the achievable signal-to-noise ratio. It also restricted the devices to relatively large sizes in terms of footprint and weight. These limitations and 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) well above 1 THz.
The objective of the 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. The program will focus on the developments of two critical THz technical areas.
Terahertz Transistor Electronics. The program will aggressively develop multi-THz InP HBT and InP HEMT transistor technologies to enable TMICs. In addition, THz low-loss inter-element interconnect and integration technologies will also be developed to build compact THz transmitter and receiver modules.
Terahertz High Power Amplifier Modules. Compact, micromachined vacuum electronics devices will be developed to produce a significant increase of output power at frequencies beyond 1.0 THz and to radiate this energy at an antenna.
The success of the THz Electronics program will lead to revolutionary applications by enabling coherent THz processing techniques such as THz imaging systems, sub-MMW, ultra-wideband, ultra-high-capacity communication links and sub-MMW, single-chip widely-tunable synthesizers for explosive detection spectroscopy. The program manager is Dr. John Albrecht


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