Silicon Micromachining Enabling High-Q Filter Solutions from D-Band to THz Frequencies

Silicon micromachining is a key enabling fabrication technology for high performance components and system integration at advanced frequencies from 100GHz to THz frequencies. Since micromachined waveguides have among the lowest losses reported in any technology (0.07 dB/mm at 300GHz, 0.008 dB/mm at 150GHz) which results in very high Q-factor components, due to the high fabrication accuracy down to micrometers, and due to the capability of manufacturing very high aspect ratio 3-dimensional geometries, silicon-micromachining provides outstanding performance for cavity resonators and complex filters based on such resonators. This talk summarizes the latest achievements in micromachined filters at sub-THz frequencies, including the first 1% fractional-bandwidth filters above 300GHz, demonstrated for a 4-pole filter at 700GHz achieving 2.5dB insertion loss with cavity resonators with an unloaded Q-factor of 950, and a D-band diplexer with 1.5dB insertion loss and 60dB adjacent channel isolation based on cavity resonators with unloaded Q-factors of 1600. The talk will also investigate the limitations and influence of fabrication tolerances, as well as the potential for volume manufacturability with high product uniformity, and the integration of such filters in complete micromachined sub-THz system solutions and in conventional waveguide systems.