No abstract

Thermal drift is one of the main issues limiting the performance of resonant MEMS sensors. Their impact may be minimized at several levels, such as specific system-level solutions (e.g. differential sensing) or mechanical design (e.g. privileging suspended structures). While solving these issues is essential, one should not overlook the temperature-dependence of the readout and oscillation-sustaining electronics associated to the resonators. Considering monolithic CMOS-MEMS devices, thermal drift of the electronics becomes the main challenge, when off-the-shelf building-blocks are used over a large temperature range (from −40 • C to 175 • C). In this paper, a process-voltage-temperature analysis of electronics readout is carried out to illustrate this issue. Proposed analysis shows that the phase-difference between the motional signals decreases monotonically with temperature. In extreme voltage-temperature conditions for −3σ variability, phase-difference achieves −7.2 • at 175 • C, V DD = 1.62 V; and 5 • at −40 • C, V DD = 1.98 V. This result highlights the need of CMOS / MEMS co-design and optimization tools, for improving the thermal stability of resonant sensors in high-end, extreme environments such as automotive applications.