Micromachined 38 GHz cavity resonator and filter with rectangular-coaxial feed-lines

Micromachined, multilayer cavity resonators and filters at 38 GHz are demonstrated. Each layer is made of gold-coated silicon, structured by deep reactive etching. Two external coupling structures by coaxial feed lines are proposed to suit the fabrication process. The measured resonator gives an unloaded Q-value of 343 at 38 GHz. Methods to further improve the resonator quality-factors are discussed. The measured insertion loss of the filter is 1.01 dB, the 3 dB bandwidth is from 36.53 to 39.13 GHz, and the return loss is better than 215 dB over the frequency range from 37.0 to 38.6 GHz.