200 AND 400 GHZ SCHOTTKY DIODE MULTIPLIERS FABRICATED WITHINTEGRATED AIR-DIELECTRIC 'SUBSTRATELESS' CIRCUITRY

摘要

A novel semiconductor fabrication process has been developed at the Jet PropulsionLaboratory for millimeter and submillimeter-wave monolithic integrated circuits. Theprocess integrates the active devices, Schottky diodes, with planar metallic transmissionlines. To reduce the RF losses in the passive circuitry, the semiconductor substrate underthe transmission lines is etched away, leaving the metal suspended in air and held only byits edges on a semiconductor frame. The frame also allows the circuit to be handled andmounted easily, and makes the whole structure more robust. Moreover, this technologyallows for the diodes to be positioned precisely with respect to the circuitry and can bescaled for higher frequency applications. Metallic beam-leads are used extensively onthe structure to provide mechanical handles as well as current paths for DC groundingand diode biasing. To demonstrate the utility of this technology, broadband balancedplanar doublers based on the concepts in [1] have been designed in the 200 and 400 GHzrange. Extensive simulations were performed to optimize the diodes and design thecircuits around our existing device fabrication process. The 368-424 GHz circuits weremeasured and achieve 15% peak efficiency at 369 GHz. The 3-db bandwidth of the fixtuneddoubler is around 9%. The maximum output power measured is around 6 mW anddrops down to 1mW at 424 GHz. This represents the highest frequency waveguide basedplanar doubler to date known to the authors.