Enhanced transduction methods for electrostatically driven MEMS resonators

Electrically addressed silicon bulk acoustic wave microresonators offer high Q solutions for applications in sensing and signal processing. However, the electrically transduced motional signal is often swamped by parasitic feedthrough in hybrid technologies. With the aim of enhancing the ratio of the motional to feedthrough current at nominal operating voltages, this paper benchmarks a variety of drive and detection principles for electrostatically driven square-extensional mode resonators operating in air and in a foundry MEMS process utilizing 2 µm gaps. A new detection technique, combining second harmonic capacitive actuation and piezoresistive detection, outperforms previously reported methods utilizing voltages as low as plusmn 3 V in air providing a promising solution for low voltage CMOS-MEMS integration