An MSI Micromechanical Differential Disk-Array Filter

A medium-scale integrated (MSI) vibrating micromechanical filter circuit that utilizes 128 radial-mode disk and mechanical link elements to achieve low motional resistance while suppressing unwanted modes and feedthrough signals has been demonstrated with a 0.06%-bandwidth insertion loss less than 2.5 dB at 163 MHz. The ability to attain an insertion loss this small for such a tiny percent bandwidth on chip is unprecedented and is made possible here by the availability of Q's >10,000 provided by capacitively transduced resonators. In particular, the MSI mechanical circuit is able to harness the high Q of capacitively transduced resonators while overcoming their impedance deficiencies via strategic mechanical circuit design methodologies, such as the novel use of wavelength-optimized resonator coupling to effect a differential mode of operation that substantially improves the stopband rejection of the filter response while also suppressing unwanted modes.