A Low Phase Jitter MEMS Oscillator With Centrally Anchored Piezoelectric Resonator for Wide Temperature Range Real-Time Clock Applications

This article describes prototype temperature compensated piezoelectric MEMS oscillators operating in the wide temperature range from C to C for real-time clock (RTC) applications. The AlN-on-Si resonator is centrally anchored at one point and designed for low power operation with a wide frequency tuning range of 5000 ppm. The oscillators exhibit a stable sinusoidal output at about 497-kHz frequency for time keeping applications with an integrated phase jitter (IPJ) being better than the best commercially available MEMS RTC oscillators for supplementary use in portable devices for clocking audio circuits. The measured oscillator performance remains relatively unchanged when comparing the wafer-level packaged (WLP) capped MEMS resonator with the uncapped one, showing great potential for a high-performance low-power RTC oscillator.Index Terms-Automatic gain control (AGC), frequency compensation, low phase jitter, low phase noise, MEMS oscillator, piezoelectric MEMS, real-time clock (RTC), wafer-level packaging, wide temperature range.