Silicon carbide MEMS oscilator

An oscillator employing a polycrystalline 3C silicon carbide (3C-SiC) folded-beam microelectromechanical resonator as a frequency-setting component with silicon discrete electronics has been designed and demonstrated. The rocking resonant mode of the resonator is chosen due to its lower motional resistance than that of the lateral resonant mode and small frequency separation between the two modes. Further analysis reveals that an increased power handling capability can be obtained by the rocking mode without an excessive mechanical motion, which is attractive for enhancing resonator durability. The resonator achieves a quality factor of 10300 at 30.2 kHz of the rocking mode resonance under 1 mTorr pressure. The oscillator outputs a sinusoidal waveform at 30.2 kHz with an output power of −17 dBm under a 10V DC bias and achieves a phase noise of −78 dBc/Hz at 12 Hz offset frequency from the carrier, limited by the resonator power handling capability and noise floor from the interface electronics. The oscillation frequency exhibits a 16 ppm stability observed over a period of 100 hours including all environment effects.