Piezoelectric aluminum nitride MEMS annular dual contour mode filter

The following work presents the analytical, numerical and experimental characterization of a novel piezoelectric aluminum nitride MEMS bandpass filter. In contrast to multi-pole filters employing distinct mechanically or electrically coupled resonator building blocks, the passband of the device in the present work is defined by the proximity of two natural contour modes of vibration in a single annular resonator. The proposed implementation, albeit currently limited to dual-pole filters, results in smaller form factors and reduces device sensitivity to across wafer fabrication tolerances. A filter with 4.8 dB of insertion loss, a 22.4 MHz center frequency, a TCF of approximately −20 ppm/°C, and 0.5% fractional bandwidth at −3 dB is demonstrated.