Five Low-Noise Stable Oscillators Referenced to the Same Multimode AlN/Si MEMS Resonator.

Abstract

We report on the first experimental demonstration of five self-sustaining feedback oscillators referenced to a single multimode resonator, using piezoelectric aluminum nitride on silicon (AlN/Si) microelectromechanical systems (MEMS) technology. Integrated piezoelectric transduction enables efficient readout of five resonance modes of the same AlN/Si MEMS resonator, at 10MHz, 30MHz, 65MHz, 95MHz, and 233MHz with quality (Q) factors of 18600, 4350, 4230, 2630, and 2138, respectively. Five stable self-sustaining oscillators are built, each referenced to one of these high-Q modes, and their mode-dependent phase noise and frequency stability (Allan deviation) are measured and analyzed. The 10, 30, 65, 95 and 233MHz oscillators exhibit low phase noise of -116, -100, -105, -106 and -92dBc/Hz at 1kHz offset frequency, respectively. The 65MHz oscillator yields Allan deviation of 4×10-9 and 2×10-7 at 1s and 1000s averaging time, respectively. The 10MHz oscillator's low phase noise holds strong promise for clock and timing applications. The five oscillators' overall promising performance also suggests suitability for multimode resonant sensing and tracking. This work also elucidates mode dependency in oscillator noise and stability, one of the key attributes of mode-engineerable resonators.