Scalable 1.1 GHz fundamental mode piezo-resistive silicon MEMS resonator

This paper demonstrates a 1.1 GHz MEMS resonator operating in fundamental mode occupying a chip area of only several mum². To our knowledge this is the smallest and first fundamental mode Si resonator operating above 1 GHz. The resonator is excited by means of an electrostatic force and the mechanical motion is detected using the piezo-resistive properties of Si. The effective impedance at resonance is orders of magnitude lower than the impedance obtained using the more common capacitive or field effect read-out. More importantly, its effective impedance is in principle insensitive to uniform and directional geometric scaling.