Patent ID: 8094841

Claim:
A capacitive detection method in a MEMS resonator comprising: vibrating a resonator with a drive signal; sensing vibration of the resonator by detecting a plurality of sidebands of an electromechanical amplitude modulation signal in a capacitive detector; and extracting amplitude of motion from a ratio of two simultaneously sensed sidebands of different order, where ω c is a carrier frequency and ω d a drive frequency applied to the resonator, where sensing vibration of the resonator by detecting a plurality of sidebands of an electromechanical amplitude modulation signal in a capacitive detector comprises detecting amplitudes of first order sidebands at frequencies ω c ±ω d and detecting amplitudes of second order sidebands at frequencies ω c ±2ω d ; and where extracting amplitude of motion from a ratio of two simultaneously sensed sidebands of different order comprises calculating a ratio of amplitudes using r =  V ω - 2  +  V ω 2   V ω - 1  +  V ω 1  or estimate using a single side pair of sidebands using r ≈  V ω - 2   V ω - 1  ≈  V ω 2   V ω 1  and calculating normalized amplitude of motion x 0 =2 r/r 2 +1.