Signal integrity in capacitive and piezoresistive single- and multi-axis MEMS gyroscopes under vibrations

The work investigates effects of external mechanical vibrations, with a frequency up to 40. kHz, on the operation of micro-electromechanical gyroscopes of different architecture and sensing technology. The analyzed devices differ (i) in the number of sensing axes (one, two or three) per single drive frame, so in the number of resonant modes within the tested vibration range, and (ii) in the used sense transduction technology (parallel-plate capacitances or piezoresistive nano-gauges). After theoretically modeling effects of vibrations occurring around the frequency of in-plane and out-of-plane resonant modes, in presence of process imperfections and nonlinearities, the work benchmarks the predictions through an extensive experimental campaign: using a shaker, vibrations of controlled amplitude and frequency are applied, in operation, to the devices along both in-plane and out-of-plane axes. Results show that, within the tested sensors, the best tolerance to vibrations, quantitatively measured in terms of angle random walk (ARW) worsening, is achieved for single-axis structures based on piezoresistive sensing. Their ARW degrades in the worst case by 1.2 times, compared to a 230-fold degradation observed in 3-axis capacitive sensors.