Design and test of 3 GHz, fundamental mode STW resonators on quartz

Surface transverse wave (STW) resonators, based on the propagation of high velocity shear horizontal waves on Y-rotated quartz are designed, fabricated and tested. A model is presented to predict the resonant frequency of a 3-grating structure as a function of design parameters such as periodicities, metal thickness, finger-to-gap ratio. Experimental devices have been fabricated by direct e-beam lithography with linewidth geometries in the range of 0.3-0.5 /spl mu/m, operating frequency of 3 GHz in fundamental mode. Two different designs using either a quasi synchronous structure (type 1) or a change of periodicity inside the cavity (type 2) have been tested. Best results obtained at 3 GHz are: unloaded Q-factor Qu=2420, insertion loss I.L.=-10.3 dB (type 1) and Qu=1920, I.L.=-9.5 dB (type 2). The best experimental factor of merit Qu/spl times/f=7.5/spl times/10/sup 12/ is close to the best results already published for quartz STW resonators.