Micromechanical tuning elements for submillimeter wave integrated circuits

Citation

Lubecke, Victor Manuel (1996) Micromechanical tuning elements for submillimeter wave integrated circuits. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/g8rb-ds84. https://resolver.caltech.edu/CaltechETD:etd-12182007-135252

Abstract

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Monolithic integrated circuit technology promises a practical means for realizing reliable and reproducible planar millimeter and submillimeter wave circuits. Planar circuits are fabricated through photolithographic techniques, which allow for the cost-effective production of intricate designs not possible with waveguide technology. Such circuits however, do not typically allow for post-fabrication optimization of performance. This can be a critical problem for the millimeter and submillimeter band, where device parasitics and fabrication tolerances are difficult to control and characterize. In this thesis, a micromechanical tuning element suitable for integration in a variety of monolithic millimeter and submillimeter wave circuits is presented. It is called a sliding planar backshort (SPB) and it can be fabricated as an integral part of a dielectric-coated coplanar transmission line. The SPB forms a movable short-circuit over a useful bandwidth, which allows for the variation of the transmission line's electrical length. A semiempirical approach was employed in its design. Measurements of [...] for the SPB at 2 GHz, were better than -0.5 dB over a bandwidth of at least 50% on both coplanar strip and coplanar waveguide transmission lines. A frequency-scaled version of the SPB was photolithographically fabricated and tested in a planar quasi-optical 100 GHz detector circuit. The response of a Schottky diode was successfully varied over a range of almost 14 dB, creating a 3 dB improvement over the untuned response. A technique for fabricating a micromechanical version of the SPB was developed. Two of these SPB's were fabricated as integral parts of a quasi-optical 620 GHz monolithic integrated detector circuit, where they were used to vary the measured response over a range of almost 15 dB. Such tuning elements can be used for characterizing developmental circuits, and for optimizing the in-use performance of various millimeter and submillimeter wave integrated circuits.

Thesis Files