Indium Phosphide Gunn Devices (26-60 GHz).
Interim rept. no. 2, 1 Jan-30 Jun 78,
VARIAN ASSOCIATES PALO ALTO CALIF CENTRAL RESEARCH LAB
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The research and development program described in this interim report is directed towards the development of InP materials and devices for low noise, broad bandwidth amplifier operation in the 26.5 to 40.0 GHz and the 40.0 to 60.0 GHz bands. The application of InP for CW transferred electron oscillators and amplifiers in the millimeter wave range provides significant performance improvements over the more widely utilized GaAs devices. In particular, InP is a superior material in several respects. It has a current peak-to-valley ratio of 3.5 as opposed to 2.5 for GaAs. This, in theory will provide higher oscillator conversion efficiencies. In addition, the peak-to-valley degrades less rapidly with temperature than GaAs and the thermal conductivity is greater, thus favoring CW operation. Due to the high effective transit velocity 1.3 x 10 to the 7th power cmsec and fast intervalley scattering, longer active regions and higher ultimate frequency limitations should favor InP for millimeter wave applications. Finally, InP reflection amplifiers have demonstrated extremely low noise figures as low as 7.5 dB, which have been attributed to the lower ratio of electron diffusion to mobility in this material.
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