Microwave reflectometry: A high-resolution technique for measuring vibration of capacitive microresonators

The paper proposes a novel technique for measuring the vibration of capacitive microelectromechanical resonators. Based on microwave reflectometry in the gigahertz range, the technique offers signal-to-noise ratio greater than 100 dB for the studied device and it rejects any parasitic crosstalk due to stray capacitances. Experiments demonstrate that amplitude resolution better than 10 fm/√Hz is achieved, which competes with standard optical interferometry. The technique is particularly appropriate for electrical characterization of MEMS devices but also for signal processing of resonant sensors when large-bandwidth, high signal-to-noise ratio and fully electrical detection is required.