Micromechanical "hollow-disk" ring resonators

A vibrating polysilicon micromechanical "hollow-disk" ring resonator obtained by removing quadrants of material from a solid disk resonator, but purposely leaving intact beams of material to non-intrusively support the structure, has been demonstrated in several vibration modes spanning frequencies from HF (24.4 MHz), to VHF (72.1MHz), to UHF (1.169 GHz), with Q\´s as high as 67,519, 48,048, and 5,846, respectively. Furthermore, the use of notched support attachments closer to actual extensional ring nodal points raises the Q to 14,603 at 1.2 GHz, which is the highest yet achieved past 1 GHz, and which clearly illustrates the utility of notching for substantially higher Q. At 1.2 GHz, a combination of high Q and larger capacitive transducers allows the notched version to achieve an R_x of only 282 kΩ, which is 12X smaller than achieved by previous pure polysilicon surface-micromachined solid disk resonators in the GHz range.