Band-pass magnetostatic wave resonators on micromachined silicon substrate

Bulk and micromachined magnetostatic wave frequency tunable resonators have been designed, realized, and tested. Four resonator configurations, two on a silicon bulk substrate and other two on a micromachined silicon membrane, have been characterized and compared by measuring their S parameter responses at different dc magnetic bias fields. The frequency has been swept between 2 GHz and 5 GHz for silicon bulk resonators and between 2 GHz and 6.5 GHz for the resonators supported by the silicon membrane. By using the membrane technological solution, the insertion losses for membrane supported resonators decrease by about 18 dB with respect to the bulk silicon supported ones. Moreover, the quality factor measured for these configurations was Q(L)approximate to450, about twice that for silicon bulk supported straight edge resonators. The obtained results demonstrate both: (i) the possibility to combine the magnetostatic wave technology with the micromachining one, and (ii) the improvement of the electrical performances for the resonators supported on a silicon membrane, with a strong decrease in the insertion losses and a doubling of the value for the quality factor. Finally, the obtained electrical response is quite good as compared to the classical alumina-based devices, with the novelty to have realized the resonators in an all-silicon environment. (C) 2004 American Institute of Physics.