The use of a stress-buffered array-composite of six 13.4-μm radius capacitive-gap transduced radial-contour mode polysilicon micromechanical disk resonators with 36.1-nm electrode-to-resonator gaps has enabled a Pierce oscillator centered at 199.2 MHz with phase noise marks of -104.7dBc/Hz at 1-kHz offset and -149.6dBc/Hz far from the carrier, sufficient for smartphones. The 12-kHz to 20-MHz integrated jitter is 163.3fs, which yields an excellent jitter FoM of -251dB. The key to this demonstration is the use of λ couplers to affect a 0° phase shift across the array terminals; and electrodeless resonators to buffer the effect of post-fabrication stress that otherwise might short disks to their electrodes when gaps are very small.
July 19, 2020
Conference Paper (Proceedings)
Q. Xie, S. Afshar, A. Ozgurluk, and C. T.-C. Nguyen, “199-MHz polysilicon micromechanical disk array-composite oscillator,” Proceedings, IEEE Joint Conf. of the IEEE Int. Frequency Contr. Symp. & IEEE Int. Symp. on Applications of Ferroelectrics, Virtual Conference, July 19-23, 2020, DOI: 10.1109/IFCS-ISAF41089.2020.9234862. (best paper award winner)