Millimeter wave semiconductor diode detectors, mixers, and frequency multipliers

The devices described include video detectors, mixers, harmonic mixers, and harmonic generators. A general discussion of the theoretical potential and limitations of these diodes is given, based on the equivalent circuit representation. This model is shown by experimental results to be valid up through 600 GHz. Diode materials, structures and forming techniques are described which have resulted in significantly improved electrical performance, as well as improved reliability and repeatability. Experimental results are quoted for detector sensitivities from 70 through 420 GHz, fundamental mixer conversion losses from 35 through 300 GHz, harmonic mixer conversion losses from 93 through 600 GHz, and harmonic generation efficiencies from fundamental frequencies of 60 through 140 GHz. The repeatability of mixer performance indicates that construction of balanced mixers is now feasible throughout the millimeter wavelength region. The improved harmonic mixer conversion losses permit construction of practical superheterodyne receivers at frequencies where local oscillator sources are impractical or unavailable. The harmonic generation capability at high frequencies (for example, at 140 GHz, one mW with diodes in the variable resistance mode and 15 mW with diodes in the varactor mode) is seen to permit the extension of frequencies for solid-state oscillators. If full advantage is taken of the capabilities of these devices, a large variety of millimeter wave systems can be assembled, including high resolution raders, high thermal sensitivity radiometers, broad bandwidth communication systems, as well as laboratory systems for mearsurement use or spectroscopic studies.