An Ultra Low-Loss Silicon-Micromachined Waveguide Filter for D-Band Telecommunication Applications
A very low-loss micromachined waveguide bandpass filter for use in D-band (110–170GHz) telecommunication applications is presented. The 134–146GHz filter is implemented in a silicon micromachined technology which utilises a double H-plane split, resulting in significantly lower insertion loss than conventional micromachined waveguide devices. Custom split-blocks are designed and implemented to interface with the micromachined component. Compact micromachined E-plane bends connect the split-blocks and DUT. The measured insertion loss per unit length of the waveguide technology (0.008–0.016dB/mm) is the lowest reported to date for any micromachined waveguide at D-band. The fabricated 6-pole filter, with a bandwidth of 11.8GHz (8.4%), has a minimum insertion loss of 0.41dB, averaging 0.5dB across its 1dB bandwidth, making it the lowest-loss D-band filter reported to date in any technology. Its return loss is better than 20dB across 85% of the same bandwidth. The unloaded quality factor of a single cavity resonator implemented in this technology is estimated to be 1600.