Frequency Stability and Noise Characteristics of Ultra-High Frequency (UHF) Nanoelectromechanical Resonators

Nanoelectromechanical silicon carbide doubly-clamped beam vibrating resonators operating in the ultra-high frequency (UHF) band, with resonance frequencies of 395MHz, 411MHz, 428MHz, and 482MH, and quality factors (Q’s) of 2000~3000, have been demonstrated. The readout of electromechanical resonances from the nanodevices is integrated with a low-noise phase-locked loop to implement real-time resonance frequency locking and tracking, with which the frequency stability and phase noise of the resonators are measured. The measured frequency stability shows typical crystal resonator behavior, and represents unprecedented mass sensitivity (in 10g ~ 10g scale) achieved by nanoelectromechanical resonant mass sensors. The achievable lowest phase noise of the system is ultimately determined by the thermomechanical noise of the resonator device, but presently limited by the thermal noise and other noise processes of the measurement electronic system.